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Business Combinations Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2018	Jan. 05, 2018
Business Acquisition [Line Items]
Payments to acquire businesses, gross			$ 802,500
Goodwill acquired		$ 570,790
SIlver Spring Networks, Inc. [Member]
Business Acquisition [Line Items]
Purchase price, net of cash				$ 809,215
Cash acquired from acquisition			$ 97,800
Equity interest issued				$ 6,700
Goodwill acquired		570,790
Business acquisition, transaction costs		15,600
Integration costs	$ 9,400	$ 68,300