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Schedule of Business Acquisitions, by Acquisition [Table Text Block]

The following reflects our preliminary allocation of purchase price as of January 5, 2018:



	Fair Value			Weighted Average Useful Life
	(in thousands)			(in years)
Current Assets	$	86,962
Property, plant, and equipment	27,670
Other long-term assets ⁽¹⁾	(830		)

Identifiable intangible assets
Core-developed technology	81,900			5
Customer contract and relationships	133,500			10
Trademark and trade names	10,800			3
Total identified intangible assets subject to amortization	226,200			8
In-process research and development (IPR&D)	14,400
Total identified intangible assets	240,600

Goodwill	572,499
Current liabilities	(91,857		)
Customer contract and relationships	(23,900		)	5
Long-term liabilities	(1,928		)
Total net assets acquired	$	809,216


⁽¹⁾	Reflects adjustments to deferred tax assets and liabilities, net as a result of the acquisition, and is classified as part of our overall consolidated deferred tax asset. This negative deferred tax asset more than offsets the fair value of other noncurrent assets acquired.

Summary of Significant Accounting Policies Cash, Cash Equivalent, and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 19, 2018	Dec. 31, 2017	Dec. 22, 2017	Mar. 31, 2017	Dec. 31, 2016
Restricted Cash and Cash Equivalents Items [Line Items]
Senior Notes		$ 100,000		$ 300,000
Cash and cash equivalents	$ 143,951		$ 176,274		$ 187,928
Restricted Cash, Current	51				0
Restricted Cash, Noncurrent	1,466		311,010		0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	145,468		487,335		$ 187,928	$ 133,565
Senior Notes [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Senior Notes	$ 400,000		$ 300,000
Debt Instrument, Interest Rate, Stated Percentage			5.00%

Summary of Significant Accounting Policies New Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 19, 2018	Dec. 31, 2017	Dec. 22, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Senior Notes		$ 100,000		$ 300,000
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption			$ 10,900
Accounting Standards Update 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption			900
Senior Notes [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Senior Notes	$ 400,000		$ 300,000
Debt Instrument, Interest Rate, Stated Percentage			5.00%

Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income (loss) available to common shareholders	$ (145,666)	$ 15,845
Weighted average common shares outstanding - Basic	38,945	38,474
Dilutive effect of stock-based awards	0	741
Weighted average common shares outstanding - Diluted	38,945	39,215
Earnings (loss) per common share - Basic	$ (3.74)	$ 0.41
Earnings (loss) per common share - Diluted	$ (3.74)	$ 0.40

Earnings Per Share Stock-based Awards (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Stock-based awards excluded from diluted EPS calculation (antidilutive)	1.0	0.2

Certain Balance Sheet Components Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accounts Receivable, Net, Current [Abstract]
Trade receivables (net of allowance of $4,774 and $3,957)	$ 448,211	$ 369,047
Unbilled receivables	33,178	28,982
Total accounts receivable, net	$ 481,389	$ 398,029

Certain Balance Sheet Components Accounts Receivable Allowance for Bad Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts Receivable, Net, Current [Abstract]
Allowance	$ 4,774	$ 3,957	$ 3,424	$ 3,320

Certain Balance Sheet Components Summary of the Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounts Receivable, Net, Current [Abstract]
Beginning balance	$ 3,957	$ 3,320
Provision for Doubtful Accounts	920	303
Accounts written-off	(258)	(330)
EffectsOfChangeInExchangeRates	155	131
Ending balance	$ 4,774	$ 3,424

Certain Balance Sheet Components Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Inventory, Net [Abstract]
Materials	$ 132,990	$ 126,656
Work in process	8,700	9,863
Finished goods	67,683	57,316
Total inventories	$ 209,373	$ 193,835

Certain Balance Sheet Components Property, Plant, and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment, Net [Abstract]
Machinery and equipment	$ 332,055	$ 310,753
Computers and software	111,227	104,384
Buildings, furniture, and improvements	150,049	135,566
Land	16,638	18,433
Construction in progress, including purchased equipment	41,959	39,946
Total cost	651,928	609,082
Accumulated depreciation	(417,004)	(408,314)
Property, plant, and equipment, net	$ 234,924	$ 200,768

Certain Balance Sheet Components Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Depreciation Expense [Line Items]
Depreciation	$ 13,332	$ 9,829

Intangible Assets Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Intangible Assets [Line Items]
Gross Assets	$ 1,025,830	$ 769,851		$ 669,896
Accumulated Amortization	(714,446)	(674,623)
Net Assets	311,384	95,228
Intangible Assets, Net (Excluding Goodwill)	318,984	95,228
Intangible Assets, Gross (Excluding Goodwill)	1,033,430		$ 686,064
Finite-lived intangible liabilities, Gross	(23,900)	0	$ 0	$ 0
Finite-Lived Intangible Liabilities, Accumulated Accretion	1,304	0
Finite-Lived Intangible Liabilities, Net	(22,596)	0
Core-developed technology [Member]
Intangible Assets [Line Items]
Gross Assets	531,263	429,548
Accumulated Amortization	(423,634)	(399,969)
Net Assets	107,629	29,579
Customer contracts and relationships [Member]
Intangible Assets [Line Items]
Gross Assets	400,566	258,586
Accumulated Amortization	(210,757)	(197,582)
Net Assets	189,809	61,004
Trademarks and trade names [Member]
Intangible Assets [Line Items]
Gross Assets	82,337	70,056
Accumulated Amortization	(68,982)	(66,004)
Net Assets	13,355	4,052
Other Intangible Assets [Member]
Intangible Assets [Line Items]
Gross Assets	11,664	11,661
Accumulated Amortization	(11,073)	(11,068)
Net Assets	591	593
In Process Research and Development [Member]
Intangible Assets [Line Items]
Gross Assets	7,600	0
Accumulated Amortization	0	0
Net Assets	$ 7,600	$ 0

Summary of Intangible Asset Account Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Total Intangible Assets [Abstract]
Beginning balance, intangible assets, gross	$ 769,851	$ 669,896
Finite-lived Intangible Assets Acquired	240,600	0
Effect of change in exchange rates	22,979	16,168
Intangible Assets, Gross (Excluding Goodwill)	1,033,430	686,064
Finite-lived intangible liabilities, Gross	(23,900)	0	$ 0	$ 0
Finite-Lived Intangible Liabilities Acquired	(23,900)	0
Finite-Lived Intangible Liabilities, Foreign Currency Translation Gain Loss	$ 0	$ 0

Intangible Assets Estimated Future Annual Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Intangible Assets [Abstract]
2018 (amount remaining at March 31, 2018)	$ 58,564
2019	72,345
2020	52,265
2021	36,649
2022	26,317
Beyond 2022	65,244
Total intangible assets subject to amortization (accretion)	311,384	$ 95,228
2018 (amount remaining at March 31, 2018)	(3,913)
2019	(8,233)
2020	(8,028)
2021	(1,963)
2022	(459)
Beyond 2022	0
Finite-Lived Intangible Liabilities, Net	(22,596)	$ 0
2018 (amount remaining at March 31, 2018)	54,651
2019	64,112
2020	44,237
2021	34,686
2022	25,858
Beyond 2022	65,244
Total intangible assets subject to amortization (accretion)	$ 288,788

Intangible Assets Intangible Assets Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 05, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 17,740	$ 4,549
Business Acquisition, Percentage of Voting Interests Acquired			100.00%
In process research and development completed	$ 6,800

Schedule of Goodwill Allocated to Reporting Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2018
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	$ 1,232,229
Accumulated impairment losses, at beginning of period	(676,467)
Goodwill, net, at beginning of period	555,762
Goodwill acquired	572,499
Effect of change in exchange rates	14,496
Goodwill before impairment, at end of period	1,843,857
Accumulated impairment losses, at end of period	(701,100)
Goodwill, net, at end of period	555,762	$ 1,142,757
Electricity Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	500,625
Accumulated impairment losses, at beginning of period	(386,384)
Goodwill, net, at beginning of period	114,241
Goodwill acquired	0
Effect of change in exchange rates	1,031
Goodwill before impairment, at end of period	514,057
Accumulated impairment losses, at end of period	(398,785)
Goodwill, net, at end of period	114,241	115,272
Gas Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	352,703
Accumulated impairment losses, at beginning of period	0
Goodwill, net, at beginning of period	352,703
Goodwill acquired	0
Effect of change in exchange rates	10,788
Goodwill before impairment, at end of period	363,491
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	352,703	363,491
Water Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	378,901
Accumulated impairment losses, at beginning of period	(290,083)
Goodwill, net, at beginning of period	88,818
Goodwill acquired	0
Effect of change in exchange rates	2,560
Goodwill before impairment, at end of period	393,693
Accumulated impairment losses, at end of period	(302,315)
Goodwill, net, at end of period	88,818	91,378
Networks Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	0
Accumulated impairment losses, at beginning of period	0
Goodwill, net, at beginning of period	0
Goodwill acquired	572,499
Effect of change in exchange rates	117
Goodwill before impairment, at end of period	572,616
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	$ 0	$ 572,616

Schedule of Debt (Details) - USD ($) $ in Thousands	3 Months Ended
Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 19, 2018	Dec. 31, 2017	Dec. 22, 2017
Debt Instrument [Line Items]
Senior Notes		$ 100,000		$ 300,000
Total debt	$ 745,777
Current portion of debt	16,250		$ 19,688
Long-term debt	1,105,538		593,572
2018 (amount remaining at March 31, 2018)	12,188
2019	28,438
2020	44,777
2021	60,937
2022	65,000
2023	534,437
Secured Debt [Member]
Debt Instrument [Line Items]
Total debt	1,145,777		619,477
Current portion of debt	16,250		19,688
Long-term debt	1,105,538		593,572
USD Denominated Term Loan [Member]
Debt Instrument [Line Items]
USD denominated term loan	650,000		194,063
Deferred Finance Costs, Noncurrent, Net	5,912		629
Line of Credit [Member]
Debt Instrument [Line Items]
Multicurrency revolving line of credit	95,777		125,414
Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes	400,000		300,000
Deferred Finance Costs, Noncurrent, Net	$ 18,077		$ 5,588
EURIBOR [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.00%
Debt Instrument, Basis Spread on Variable Rate	2.00%

Credit Facility Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Jan. 05, 2018	Jun. 23, 2015
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 1,200,000	$ 725,000
Line of Credit Facility, Maximum Borrowing Capacity			500,000
Swingline sub-facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			50,000
Line of credit facility, amount outstanding	$ 0
USD Denominated Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 650,000
Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding	95,777	$ 125,414
Line of Credit Facility, Remaining Borrowing Capacity	357,864	$ 342,705
Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 300,000
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Collateral	All obligations under the 2018 credit facility are guaranteed by Itron, Inc. and material U.S. domestic subsidiaries and are secured by a pledge of substantially all of the assets of Itron, Inc. and material U.S. domestic subsidiaries, including a pledge of their related assets. This includes a pledge of 100% of the capital stock of material U.S. domestic subsidiaries and up to 66% of the voting stock (100% of the non-voting stock) of first-tier foreign subsidiaries. In addition, the obligations of any foreign subsidiary who is a foreign borrower, as defined by the 2018 credit facility, are guaranteed by the foreign subsidiary and by its direct and indirect foreign parents.
Minimum [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.18%
Maximum [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.35%
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	the LIBOR rate
Debt Instrument, Basis Spread on Variable Rate	2.00%	1.25%
Applicable Interest Rate	3.88%
EURIBOR [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	EURIBOR rate
Debt Instrument, Basis Spread on Variable Rate		1.25%
Applicable Interest Rate		1.25%
Alternate base rate (1) [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	the prime rate
Alternate base rate (2) [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	the Federal Reserve effective rate
Debt Instrument, Basis Spread on Variable Rate	0.50%
Alternate base rate (3) [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	one-month LIBOR
Debt Instrument, Basis Spread on Variable Rate	1.00%
Alternate base rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	Alternate Base Rate

Debt Senior Note Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended		36 Months Ended	37 Months Ended
	Jan. 14, 2023	Jan. 14, 2022	Jan. 15, 2026	Jan. 14, 2021	Mar. 31, 2018	Jan. 19, 2018	Dec. 31, 2017	Dec. 22, 2017
Debt Instrument [Line Items]
Senior Notes						$ 100,000		$ 300,000
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage							5.00%
Senior Notes					$ 400,000		$ 300,000
Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage		102.50%
Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	101.25%
Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage			100.00%
Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage				105.00%
Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption, Description				0.35
Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption, Description				0.65

Derivative and Nonderivative Hedging Instrument Fair Value Disclosure (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Asset Derivatives [Abstract]
Gross Amounts of Recognized Assets Presented in the Consolidated Balance Sheets	$ 4,532	$ 2,900
Liability Derivatives [Abstract]
Total liability derivatives	356	289
Not Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Asset Derivatives [Abstract]
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	44	41
Not Designated as Hedging Instrument [Member] \| Other Current Liabilities [Member]
Liability Derivatives [Abstract]
Foreign exchange forward contracts	356	289
Interest Rate Swap [Member] \| Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Asset Derivatives [Abstract]
Interest Rate Derivative Assets, at Fair Value	1,303	658
Interest Rate Swap [Member] \| Designated as Hedging Instrument [Member] \| Other Noncurrent Assets [Member]
Asset Derivatives [Abstract]
Interest Rate Derivative Assets, at Fair Value	2,226	1,712
Interest Rate Cap [Member] \| Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Asset Derivatives [Abstract]
Interest Rate Derivative Assets, at Fair Value	74	17
Interest Rate Cap [Member] \| Designated as Hedging Instrument [Member] \| Other Noncurrent Assets [Member]
Asset Derivatives [Abstract]
Interest Rate Derivative Assets, at Fair Value	310	179
Interest Rate Cap [Member] \| Not Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Asset Derivatives [Abstract]
Interest Rate Derivative Assets, at Fair Value	111	25
Interest Rate Cap [Member] \| Not Designated as Hedging Instrument [Member] \| Other Noncurrent Assets [Member]
Asset Derivatives [Abstract]
Interest Rate Derivative Assets, at Fair Value	$ 464	$ 268

Activity of Hedging Instruments in Accumulated OCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	$ (170,478)
Unrealized gain (loss) on derivative instruments	1,183	$ 60
Realized losses reclassified into net income (loss)	(14)	232
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(152,595)
Accumulated Net Gain (Loss) from Derivative and Nonderivative Instruments Designated as Hedging Instruments [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(13,414)	(14,337)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	$ (12,245)	$ (14,045)

Offsetting of Derivative Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Offsetting Derivative Assets [Abstract]
Gross Amounts of Recognized Assets Presented in the Consolidated Balance Sheets	$ 4,532	$ 2,900
Derivative Financial Instruments Not Offset in the Consolidated Balance Sheets	(128)	(90)
Cash Collateral Received Not Offset in the Consolidated Balance Sheets	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	$ 4,404	$ 2,810

Offsetting of Derivative Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Offsetting Derivative Liabilities [Abstract]
Gross Amounts of Recognized Liabilities Presented in the Consolidated Balance Sheets	$ 356	$ 289
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(128)	(90)
Cash Collateral Pledged Not Offset in the Consolidated Balance Sheets	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 228	$ 199

Derivative Financial Instruments Narrative (Details)	3 Months Ended	12 Months Ended
Derivative Financial Instruments Narrative (Details)	Mar. 31, 2018 USD ($) contracts	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Total debt	$ 745,777,000
Net unrealized loss on hedging instruments	152,595,000		$ 170,478,000
Secured Debt [Member]
Total debt	1,145,777,000		619,477,000
Accumulated Other Comprehensive Income, Net Unrealized Gain (Loss) on Nonderivative Instruments [Member]
Net unrealized loss on hedging instruments	$ 14,380,000		$ 14,380,000	$ 14,380,000	$ 14,380,000
Number of Counterparties [Member]
Derivative Counterparties	3		3
Interest Rate Swap [Member]
Number of Interest Rate Derivatives Held \| contracts	1
Derivative, Notional Amount	$ 214,000,000
Pay fixed interest rate in interest rate swap	1.42%
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 1,300,000
Interest Rate Cap [Member]
Number of Interest Rate Derivatives Held \| contracts	3
Derivative, Notional Amount	$ 100,000,000
Derivative, Cap Interest Rate	2.00%
Derivative Purchase Price		$ 1,700,000
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ (300,000)
Forward Contracts [Member]
Description of Derivative Activity Volume	57
Foreign Exchange Contract [Member] \| Not Designated as Hedging Instrument [Member] \| Minimum [Member]
Derivative, Notional Amount	$ 93,000
Foreign Exchange Contract [Member] \| Not Designated as Hedging Instrument [Member] \| Maximum [Member]
Derivative, Notional Amount	47,500,000
London Interbank Offered Rate (LIBOR) [Member] \| Secured Debt [Member]
Total debt	$ 690,000,000

Effect of Cash Flow Derivatives on the Balance Sheet and Income Statement, Before Tax (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments Designated as Hedging Instruments [Abstract]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ 1,247	$ 181
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	19	(378)
Interest Expense [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	88	(335)
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion)	0	0
Interest Rate Cap [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	188	(84)
Interest Rate Cap [Member] \| Interest Expense [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(70)	(43)
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion)	$ 0	$ 0

Derivatives Not Designated as Hedging Relationships (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other Income (Expense) [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Foreign exchange forward contracts	$ (1,523)	$ (1,742)
Interest Rate Cap [Member] \| Interest Expense [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	$ 282	$ (126)

Schedule of Amounts Recognized in the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Plan assets in other long-term assets	$ 1,054	$ 991
Current portion of pension benefit obligation in wages and benefits payable	3,291	3,260
Long-term portion of pension benefit obligation	100,045	95,717
Pension benefit obligation, net	$ 102,282	$ 97,986

Schedule of Net Periodic Pension Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan [Abstract]
Service cost	$ 1,049	$ 928
Interest cost	609	525
Expected return on plan assets	(181)	(146)
Amortization of actuarial net loss	403	391
Amortization of unrecognized prior service costs	17	15
Net periodic benefit cost	$ 1,897	$ 1,713

Stock-Based Compensation Expense and Related Tax Benefit (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options	$ 831	$ 659
Restricted stock units	7,057	4,297
Unrestricted stock awards	207	255
Phantom stock units	690	392
Total stock-based compensation	8,785	5,603
Related tax benefit	$ 1,534	$ 1,228
Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	10,473,956
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	4,215,490

Stock Option Summary (Details) - Employee Stock Option [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
[Line Items]
Outstanding, beginning balance, Number	956	959	959
Outstanding, beginning balance, Weighted Average Exercise Price Per Share	$ 47.10	$ 45.64	$ 45.64
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	6 years 6 months	6 years 8 months 12 days	6 years 3 months 18 days	6 years 7 months 6 days
Outstanding, beginning balance, Aggregate Intrinsic Value	$ 21,965	$ 19,125	$ 19,125
Shares converted upon acquisition, number	42
Shares converted upon acquisition, Weighted Average Exercise Price	$ 51.86
Shares converted upon acquisition, Weighted Average Grant Date Fair Value	$ 14.86
Options granted, number	101	121
Granted, Weighted Average Exercise Price Per Share	$ 69.30	$ 65.55
Granted, Weighted Average Grant Date Fair Value	$ 24.83	$ 22.01
Exercised, Number	(62)	(5)
Exercised, Weighted Average Exercise Price Per Share	$ 40.31	$ 35.29
Exercised, Aggregate Intrinsic Value	$ 2,104	$ 120
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	(3)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value	$ 72.25
Expired, Number	(7)
Expired, Weighted Average Exercise Price Per Share	$ 95.96
Outstanding, ending balance, Number	1,027	1,075	956	959
Outstanding, ending balance, Weighted Average Exercise Price Per Share	$ 49.49	$ 47.92	$ 47.10	$ 45.64
Outstanding, ending balance, Aggregate Intrinsic Value	$ 24,051	$ 17,236	$ 21,965	$ 19,125
Exercisable, Number	716
Exercisable, Weighted Average Exercise Price Per Share	$ 45.96
Exercisable, Weighted Average Remaining Contractual Term	5 years 6 months
Exercisable, Aggregate Intrinsic Value	$ 19,725
Expected to Vest [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	8 years 10 months 24 days
Outstanding, ending balance, Number	308
Outstanding, ending balance, Weighted Average Exercise Price Per Share	$ 57.74
Outstanding, ending balance, Aggregate Intrinsic Value	$ 4,255

Stock Option Black Scholes Option Pricing Model Assumptions (Details) - Employee Stock Option [Member] - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Expected volatility	30.90%	32.70%
Risk-free interest rate	2.80%	2.00%
Expected term (years)	6 years 1 month 6 days	5 years 6 months
Granted, Weighted Average Grant Date Fair Value	$ 24.83	$ 22.01

Stock-Based Compensation Restricted Stock Units Summary (Details) - Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
[Line Items]
Outstanding, beginning balance, Number	556	701
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 63.72		$ 47.68
Shares converted upon acquisition, number	579
Shares converted upon acquisition, Weighted Average Grant Date Fair Value	$ 69.40
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	136	131
Weighted average fair value	$ 69.30	$ 63.12
Forfeited, Number	(28)	(3)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 68.44
Outstanding, ending balance, Number	891	512
Vested and Released [Member]
[Line Items]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	352	317
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 47.18
Released, Aggregate Intrinsic Value	$ 17,231	$ 12,066
Vested but Not Released [Member]
[Line Items]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	10
Released, Aggregate Intrinsic Value	$ 729
Expected to Vest [Member]
[Line Items]
Outstanding, ending balance, Number	788
Expected to vest, Aggregate Intrinsic Value	$ 56,369
Long Term Performance Restricted Stock Award [Member]
[Line Items]
Risk-free interest rate	2.20%	1.00%
Expected term (years)	2 years 1 month 6 days	1 year 8 months 12 days
Weighted average fair value	$ 78.56	$ 77.78

Stock-Based Compensation Long-Term Performance Restricted Stock Unit Award Monte Carlo Pricing Model Assumptions (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value	$ 69.30	$ 63.12
Long Term Performance Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	28.00%	28.00%
Risk-free interest rate	2.20%	1.00%
Expected term (years)	2 years 1 month 6 days	1 year 8 months 12 days
Weighted average fair value	$ 78.56	$ 77.78

Stock-Based Compensation Phantom Stock Units Summary (Details) - Phantom Share Units (PSUs) [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 5.7
Outstanding, beginning balance, Number	63	62
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 62.61		$ 51.88
Shares converted upon acquisition, number	21
Shares converted upon acquisition, Weighted Average Grant Date Fair Value	$ 69.40
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	31	32
Weighted average fair value	$ 69.30	$ 65.55
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	(27)	(19)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 50.19
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(1)	(2)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 69.36
Outstanding, ending balance, Number	87	73
Expected to Vest [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, ending balance, Number	85	73

Stock-Based Compensation Narrative (Details) $ in Millions	3 Months Ended
Stock-Based Compensation Narrative (Details) $ in Millions	Mar. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)
Employee Stock Option [Member]
[Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized \| $	$ 5.0
Unrecognized compensation expense, Expected weighted average period for recognition (years)	1 year 9 months 18 days
Restricted Stock Units (RSUs) [Member]
[Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized \| $	$ 61.3
Unrecognized compensation expense, Expected weighted average period for recognition (years)	2 years 4 months 24 days
Phantom Share Units (PSUs) [Member]
[Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized \| $	$ 5.7
Unrecognized compensation expense, Expected weighted average period for recognition (years)	2 years 2 months 12 days
Deferred Compensation Share-based Arrangements, Liability, Current \| $	$ 0.6	$ 1.7
Employee Stock Purchase Plan [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	331,993
Stock Incentive Plan [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	10,473,956
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	4,215,490
Reduction in stock options available for issue	1
Authorized share reserve reduction in awards other than stock options or share appreciation rights available for issue, conversion ratio	1.7
SSNI Plan [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	730,457
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	142,336

Income Tax Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
Income Tax Contingencies (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Uncertainties [Abstract]
Net interest and penalties expense	$ 424	$ 206
Accrued interest	3,155		$ 2,706
Accrued penalties	2,513		2,426
Unrecognized tax benefits related to uncertain tax positions	76,120		56,702
The amount of unrecognized tax benefits that, if recognized, would affect our effective tax rate	$ 74,671		$ 55,312

Income Taxes Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
Income Taxes Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Examination [Line Items]
Effective Income Tax Rate Reconciliation, Percent	7.00%	36.00%
Unrecognized Tax Benefits	$ 76,120		$ 56,702
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%
Minimum [Member]
Income Tax Examination [Line Items]
Open Tax Year	2000
Maximum [Member]
Income Tax Examination [Line Items]
Open Tax Year	2015
SSNI Plan [Member]
Income Tax Examination [Line Items]
Unrecognized Tax Benefits	$ 16,400

Commitments and Contingencies Available Lines of Credit, Outstanding Standby Letter of Credits, and Bonds (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 05, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit		$ 500,000
Line of Credit Facility, Capacity remaining to support letters of credit	$ 253,641		$ 218,119
Credit Facility [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit	500,000		500,000
Long-term Line of Credit	95,777		125,414
Letters of Credit Outstanding, Amount	(46,359)		(31,881)
Unsecured Multicurrency Revolving Lines of Credit [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit	114,160		110,477
Letters of Credit Outstanding, Amount	(21,471)		(21,030)
Short-term borrowings	(1,776)		(916)
Line of Credit Facility, Remaining Borrowing Capacity	90,913		88,531
Surety Bond [Member]
Line of Credit Facility [Line Items]
Unsecured surety bonds in force	52,639		51,344
Line of Credit [Member]
Line of Credit Facility [Line Items]
Long-term Line of Credit	95,777		125,414
Line of Credit Facility, Remaining Borrowing Capacity	$ 357,864		$ 342,705

Commitments and Contingencies Warranty Account Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Beginning balance	$ 34,862	$ 43,302
Assumed liabilities from acquisition	5,742	0
New product warranties	818	2,361
Other changes/adjustments to warranties	4,044	1,682
Claims activity	(4,108)	(6,351)
Effect of change in exchange rates	621	542
Ending balance	41,979	41,536
Less: current portion of warranty	26,533	23,500
Long-term warranty	$ 15,446	$ 18,036

Commitments and Contingencies Warranty Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Total warranty expense	$ 4,862	$ 4,043

Commitments and Contingencies Health Benefit Plan Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
US Employee Group Health Insurance Expense	$ 8,680	$ 8,754

Commitments and Contingencies Incurred But Not Reported Health Benefit Cost Accrual (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
IBNR Accrual	$ 2,911	$ 2,664

Restructuring Restructuring Expected Costs - 2018 Projects (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring	$ 87,865	$ 3,052
2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	104,493
Restructuring	87,993
Restructuring and Related Cost, Expected Cost Remaining	16,500
Asset Impairment and Net (Gain) Loss on Sale or Disposal [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	47
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	832
Other Restructuring [Member] \| 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	16,500
Restructuring	0
Restructuring and Related Cost, Expected Cost Remaining	16,500
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	86,986
Employee Severance [Member] \| 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	87,993
Restructuring	87,993
Restructuring and Related Cost, Expected Cost Remaining	0
Corporate, Non-Segment [Member] \| 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	8,146
Restructuring	8,146
Restructuring and Related Cost, Expected Cost Remaining	0
Water Operating Segment [Member] \| 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	23,712
Restructuring	17,712
Restructuring and Related Cost, Expected Cost Remaining	6,000
Gas Operating Segment [Member] \| 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	51,929
Restructuring	42,929
Restructuring and Related Cost, Expected Cost Remaining	9,000
Electricity Operating Segment [Member] \| 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	20,706
Restructuring	19,206
Restructuring and Related Cost, Expected Cost Remaining	$ 1,500

Restructuring Expected Costs - 2016 Projects (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring	$ 87,865	$ 3,052
2016 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	59,584
Restructuring and Related Cost, Cost Incurred to Date			$ 54,212
Restructuring	(128)
Remaining Costs to be Recognized at Period End	5,500
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	86,986
Employee Severance [Member] \| 2016 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	38,848
Restructuring and Related Cost, Cost Incurred to Date			39,855
Restructuring	(1,007)
Remaining Costs to be Recognized at Period End	0
Asset Impairment and Net (Gain) Loss on Sale or Disposal [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	47
Asset Impairment and Net (Gain) Loss on Sale or Disposal [Member] \| 2016 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	4,969
Restructuring and Related Cost, Cost Incurred to Date			4,922
Restructuring	47
Remaining Costs to be Recognized at Period End	0
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	832
Other Restructuring [Member] \| 2016 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	15,767
Restructuring and Related Cost, Cost Incurred to Date			9,435
Restructuring	832
Remaining Costs to be Recognized at Period End	5,500
Electricity Operating Segment [Member] \| 2016 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	10,919
Restructuring and Related Cost, Cost Incurred to Date			9,025
Restructuring	394
Remaining Costs to be Recognized at Period End	1,500
Gas Operating Segment [Member] \| 2016 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	31,799
Restructuring and Related Cost, Cost Incurred to Date			29,181
Restructuring	618
Remaining Costs to be Recognized at Period End	2,000
Water Operating Segment [Member] \| 2016 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	14,763
Restructuring and Related Cost, Cost Incurred to Date			13,761
Restructuring	(998)
Remaining Costs to be Recognized at Period End	2,000
Corporate, Non-Segment [Member] \| 2016 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	2,103
Restructuring and Related Cost, Cost Incurred to Date			$ 2,245
Restructuring	(142)
Remaining Costs to be Recognized at Period End	$ 0

Restructuring Related Balance Sheet Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Beginning balance, January 1, 2018	$ 40,125
Costs charged to expense	87,865	$ 3,052
Cash payments	(7,917)
Net assets disposed and impaired	(47)
Effect of change in exchange rates	1,568
Ending balance, March 31, 2018	121,594
Accrued Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Beginning balance, January 1, 2018	37,654
Costs charged to expense	86,986
Cash payments	(7,063)
Net assets disposed and impaired	0
Effect of change in exchange rates	1,566
Ending balance, March 31, 2018	119,143
Asset Impairment and Net (Gain) Loss on Sale or Disposal [Member]
Restructuring Cost and Reserve [Line Items]
Beginning balance, January 1, 2018	0
Costs charged to expense	47
Cash payments	0
Net assets disposed and impaired	(47)
Effect of change in exchange rates	0
Ending balance, March 31, 2018	0
Other Accrued Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning balance, January 1, 2018	2,471
Costs charged to expense	832
Cash payments	(854)
Net assets disposed and impaired	0
Effect of change in exchange rates	2
Ending balance, March 31, 2018	$ 2,451

Restructuring Additional Information (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Current	$ 60.3	$ 32.5
Restructuring Reserve, Noncurrent	$ 61.2	$ 7.6

Shareholders' Equity Preferred Stock (Details) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Preferred Stock, No Par Value

Shareholders' Equity Stock Repurchase Plan (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Feb. 23, 2017
Equity [Abstract]
Stock Repurchase Program, Authorized Amount		$ 50
Stock Repurchased During Period, Shares	0

Shareholders' Equity Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Before-tax amount [Abstract]
Foreign currency translation adjustment	$ 16,293	$ 15,066
Net unrealized gain (loss) on derivative instruments designated as cash flow hedges	1,436	97
Net hedging (gain) loss reclassified into net income	(19)	378
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax	420	406
Total other comprehensive income (loss), before tax	18,130	15,947
Tax (provision) benefit [Abstract]
Foreign currency translation adjustment	7	(50)
Net unrealized gain (loss) on derivative instruments designated as cash flow hedges	(253)	(37)
Net hedging (gain) loss reclassified into net income	5	(146)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax	(6)	(5)
Total other comprehensive income (loss) tax benefit	(247)	(238)
Net-of-tax amount [Abstract]
Foreign currency translation adjustment	16,300	15,016
Net unrealized gain (loss) on derivative instruments designated as cash flow hedges	1,183	60
Net hedging loss (gain) reclassified into net income	(14)	232
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax	414	401
Total other comprehensive income (loss), net of tax	$ 17,883	$ 15,709

Shareholders' Equity Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	$ (170,478)
Total other comprehensive income (loss), net of tax	17,883	$ 15,709
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(152,595)
Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(170,478)	(229,327)
OCI before reclassifications	17,483	15,076
Amounts reclassified from AOCI	400	633
Total other comprehensive income (loss), net of tax	17,883	15,709
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(152,595)	(213,618)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(128,648)	(182,986)
OCI before reclassifications	16,300	15,016
Amounts reclassified from AOCI	0	0
Total other comprehensive income (loss), net of tax	16,300	15,016
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(112,348)	(167,970)
Accumulated Other Comprehensive Income, Net Unrealized Gain (Loss) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	966	43
OCI before reclassifications	1,183	60
Amounts reclassified from AOCI	(14)	232
Total other comprehensive income (loss), net of tax	1,169	292
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	2,135	335
Accumulated Other Comprehensive Income, Net Unrealized Gain (Loss) on Nonderivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(14,380)	(14,380)
OCI before reclassifications	0	0
Amounts reclassified from AOCI	0	0
Total other comprehensive income (loss), net of tax	0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(14,380)	(14,380)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(28,416)	(32,004)
OCI before reclassifications	0	0
Amounts reclassified from AOCI	414	401
Total other comprehensive income (loss), net of tax	414	401
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	$ (28,002)	$ (31,603)

Schedule of Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 19, 2018	Dec. 31, 2017	Dec. 22, 2017	Mar. 31, 2017
Assets
Cash and cash equivalents	$ 143,951		$ 176,274		$ 187,928
Liabilities
Senior Notes		$ 100,000		$ 300,000
USD Denominated Term Loan [Member]
Liabilities
USD denominated term loan	650,000		194,063
Line of Credit [Member]
Liabilities
Multicurrency revolving line of credit	95,777		125,414
Reported Value Measurement [Member]
Assets
Cash and cash equivalents	143,951		176,274
Restricted Cash	1,517		311,061
Foreign exchange forwards	44		41
Liabilities
Senior Notes	400,000		300,000
Foreign exchange forwards	356		289
Reported Value Measurement [Member] \| USD Denominated Term Loan [Member]
Liabilities
USD denominated term loan	650,000		194,063
Reported Value Measurement [Member] \| Line of Credit [Member]
Liabilities
Multicurrency revolving line of credit	95,777		125,414
Estimate of Fair Value Measurement [Member]
Assets
Cash and cash equivalents	143,951		176,274
Restricted Cash	1,517		311,061
Foreign exchange forwards	44		41
Liabilities
Senior Notes	395,000		301,125
Foreign exchange forwards	356		289
Estimate of Fair Value Measurement [Member] \| USD Denominated Term Loan [Member]
Liabilities
Long-term Debt, Fair Value	658,796		192,295
Estimate of Fair Value Measurement [Member] \| Line of Credit [Member]
Liabilities
Line of Credit Facility, Fair Value of Amount Outstanding	97,205		124,100
Interest Rate Swap [Member] \| Reported Value Measurement [Member]
Assets
Derivative Asset, Noncurrent	3,529		2,370
Interest Rate Swap [Member] \| Estimate of Fair Value Measurement [Member]
Assets
Derivative Asset, Noncurrent	3,529		2,370
Interest Rate Cap [Member] \| Reported Value Measurement [Member]
Assets
Derivative Asset, Noncurrent	959		489
Interest Rate Cap [Member] \| Estimate of Fair Value Measurement [Member]
Assets
Derivative Asset, Noncurrent	$ 959		$ 489

Information By Segment (Details) - USD ($) $ in Thousands	3 Months Ended
Information By Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	$ 537,110	$ 432,365
Sales Revenue, Services, Net	70,111	45,227
Revenues	607,221	477,592
Gross profit	179,855	157,637
Operating Income (Loss)	(140,448)	30,827
Total other income (expense)	(16,010)	(5,766)
Income Before Income Taxes	(156,458)	25,061
Electricity Operating Segment [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	213,877	205,903
Sales Revenue, Services, Net	38,528	32,848
Revenues	252,405	238,751
Gross profit	69,975	67,250
Operating Income (Loss)	(2,768)	17,084
Gas Operating Segment [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	130,243	117,127
Sales Revenue, Services, Net	7,496	7,084
Revenues	137,739	124,211
Gross profit	43,471	50,815
Operating Income (Loss)	(28,348)	21,731
Water Operating Segment [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	125,587	109,335
Sales Revenue, Services, Net	5,607	5,295
Revenues	131,194	114,630
Gross profit	37,805	39,572
Operating Income (Loss)	(11,710)	8,804
Networks Operating Segment [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	67,403	0
Sales Revenue, Services, Net	18,480	0
Revenues	85,883	0
Gross profit	28,604	0
Operating Income (Loss)	(75,510)	0
Corporate Unallocated [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (22,112)	$ (16,792)

Segment Results Narrative (Details)	3 Months Ended
Segment Results Narrative (Details)	Mar. 31, 2018 $ / shares	Mar. 31, 2017 $ / shares
Segment Reporting [Abstract]
Number of Reportable Segments	4	3
Segment Reporting Information [Line Items]
Concentration Risk, Supplier	We currently buy a majority of our integrated circuit boards, an important component in our products, from two suppliers. Management believes that other suppliers could provide similar circuit boards, but a change in suppliers, disputes with our suppliers, or unexpected constraints on the suppliers' production capacity could adversely affect operating results.
Earnings (loss) per common share - Basic	$ (3.74)	$ 0.41
Earnings (loss) per common share - Diluted	$ (3.74)	$ 0.40

Segment Information Major Customers (Details) - Revenue [Member]	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Threshold for Reporting Customer Concentration [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	10.00%	10.00%
Customer A [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	10.00%
Customer A [Member] \| Electricity Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	22.00%	18.00%
Customer A [Member] \| Gas Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	11.00%
Customer A [Member] \| Networks Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	11.00%
Customer B [Member] \| Electricity Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	16.00%

Segment Information Revenues By Region (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2018

Mar. 31, 2017

United States and Canada [Member]

$ 607,221

$ 477,592

Europe, Middle East, and Africa [Member]

355,932

269,096

202,074

162,815

Other [Member]

^[1]

$ 49,215

$ 45,681

[1]	The Other region includes our operations in Latin America and Asia Pacific.

Depreciation and Amortization, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 31,072	$ 14,378
Electricity Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	6,525	5,311
Gas Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	4,202	4,244
Water Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	4,109	3,959
Networks Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	15,012	0
Corporate Unallocated [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 1,224	$ 864

Revenue Recognition Revenue Contract Assets and Liabilities Rollforward (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue Recognition and Deferred Revenue [Abstract]
Contract with Customer, net	$ 59,808
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination	38,816
Revenue recognized from beginning contract liability	(24,549)
Revenue recognized from amounts added in the current period	(6,352)
Increases due to amounts billed in the current period	56,051
Other adjustments	(1,243)
Contract with Customer, net	$ 122,531

Revenue Recognition Remaing Performance Obligation (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01 $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 740.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months

Revenue Recognition Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Revenue Recognition and Deferred Revenue [Abstract]
Contract with Customer, Asset, Gross	$ 14,200	$ 11,300
Contract with Customer, Liability	136,700	71,100
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue, Current	87,293	41,438
Retained Earnings (Accumulated Deficit)	(471,812)	$ (337,873)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue	15,000
Deferred Revenue, Current	6,000
Retained Earnings (Accumulated Deficit)	$ 11,000

- Definition

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

+ References + Details

Business Combinations Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Jan. 05, 2018
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 802,500
Goodwill acquired	572,499
SIlver Spring Networks, Inc. [Member]
Business Acquisition [Line Items]
Cash Acquired from Acquisition	97,800
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned			$ 6,700
Goodwill acquired	572,500
Business Acquisition, Transaction Costs	15,600
Business Combination, Integration Related Costs	$ 46,800
Comverge [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Other		$ 100,000
Cash Acquired from Acquisition		18,200
Goodwill acquired		$ 59,700

Business Combinations Purchase Price Allocation (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2018

Mar. 31, 2017

Jan. 05, 2018

Business Combination, Current Assets

$ 86,962

Business Combination, Property, Plant, and Equipment

27,670

Business Combination, Other Noncurrent Assets

^[1]

(830)

Acquired Intangible Assets, Weighted Average Useful Life

226,200

8 years

Business Combination, Intangible Assets, Other than Goodwill

240,600

Goodwill acquired

$ 572,499

Business Combination, Current Liabilities

(91,857)

Finite-Lived Intangible Liabilities Acquired

(23,900)

$ 0

Business Combination, Noncurrent Liabilities

1,928

SIlver Spring Networks, Inc. [Member]

Business Combination, Goodwill, and Liabilities Assumed, Net

Goodwill acquired

572,500

809,216

Business Acquisition, Transaction Costs

$ 15,600

Core Developed Technology [Member]

Acquired Intangible Assets, Weighted Average Useful Life

81,900

5 years

Customer Contracts And Relationships [Member]

Acquired Intangible Assets, Weighted Average Useful Life

133,500

10 years

Finite-Lived Intangible Liabilities Acquired

$ (23,900)

Acquired Finite-lived Intangible Liabilities, Weighted Average Useful Life

5 years

Trademarks and Trade Names [Member]

Acquired Intangible Assets, Weighted Average Useful Life

10,800

3 years

In Process Research and Development [Member]