Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 65,600	$ 40,755	$ 243,822	$ 68,413
Other comprehensive income (loss):
Foreign currency translation adjustments	14,347	(4,446)	16,926	3,096
Change in unrealized gains (losses) on available-for-sale securities, net of tax of $89, $388, $166, and $1,222, respectively	144	636	271	2,001
Total other comprehensive income (loss)	14,491	(3,810)	17,197	5,097
Comprehensive income	$ 80,091	$ 36,945	$ 261,019	$ 73,510