Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 79,959	$ 57,189	$ 184,884	$ 132,143
Other comprehensive income, net of tax:
Amortization of loss on cash flow hedge	215	215	646	646
Foreign currency translation adjustment	(250)	851	(1,264)	2,842
Other comprehensive (loss) income, net of tax	(35)	1,066	(618)	3,488
Comprehensive income	$ 79,924	$ 58,255	$ 184,266	$ 135,631

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

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