Consolidated Statements of Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Common Stock Including Additional Paid in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Parent [Member]	Noncontrolling Interest [Member]	SIlver Spring Networks, Inc. [Member] Common Stock Including Additional Paid in Capital [Member]	SIlver Spring Networks, Inc. [Member] Parent [Member]
Beginning balance (in shares) at Dec. 31, 2017		38,771,000
Beginning balance at Dec. 31, 2017	$ 805,632		$ 1,294,767	$ (170,478)	$ (337,873)	$ 786,416	$ 19,216
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(145,270)				(145,666)	(145,666)	396
Other Comprehensive Income (Loss), Net of Tax	17,883			17,883		17,883
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(981)						(981)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		62,000
Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense)	2,883		2,883			2,883
Stock Issued During Period, Shares, Restricted Stock Award, Gross		338,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	0		0			0
Stock Issued During Period, Shares, Share-based Compensation, Gross		2,000
Stock Issued During Period, Value, Share-based Compensation, Gross	207		207			207
Stock Issued During Period, Shares, Employee Stock Purchase Plans		8,000
Stock Issued During Period, Value, Employee Stock Purchase Plan	501		501			501
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	7,888		7,888			7,888
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	7		7			7
Adjustments to Additional Paid in Capital, Other								$ 4,140	$ 4,140
Ending balance (in shares) at Mar. 31, 2018		39,181,000
Ending balance at Mar. 31, 2018	$ 704,603		1,310,379	(152,595)	(471,812)	685,972	18,631
Beginning balance (in shares) at Dec. 31, 2018	39,498,000	39,498,000
Beginning balance at Dec. 31, 2018	$ 734,048		1,334,364	(196,305)	(425,396)	712,663	21,385
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(149)				(1,907)	(1,907)	1,758
Other Comprehensive Income (Loss), Net of Tax	(1,780)			(1,780)		(1,780)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(517)						(517)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		20,000
Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense)	889		889			889
Stock Issued During Period, Shares, Restricted Stock Award, Gross		319,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	(720)		(720)			(720)
Stock Issued During Period, Shares, Share-based Compensation, Gross		2,000
Stock Issued During Period, Value, Share-based Compensation, Gross	157		157			157
Stock Issued During Period, Shares, Employee Stock Purchase Plans		19,000
Stock Issued During Period, Value, Employee Stock Purchase Plan	869		869			869
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	$ 7,048		7,048			7,048
Stock Repurchased During Period, Shares	(165,400)
Stock Repurchased During Period, Value	$ 7,814		7,814			7,814
Ending balance (in shares) at Mar. 31, 2019	39,693,000	39,693,000
Ending balance at Mar. 31, 2019	$ 732,031		$ 1,334,793	$ (198,085)	$ (427,303)	$ 709,405	$ 22,626