Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 558,929	$ 186,678	$ 122,641
Other comprehensive income (loss):
Foreign currency translation adjustments	27,409	(5,464)	(37,887)
Change in unrealized gains (losses) on available-for-sale securities, net of tax of $378, $126, and $(598), respectively	599	207	(975)
Total other comprehensive income (loss)	28,008	(5,257)	(38,862)
Comprehensive income	$ 586,937	$ 181,421	$ 83,779