Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 144,793	$ 189,251	$ 283,224	$ 390,280
Other comprehensive income, net of tax:
Foreign currency translation adjustments	1,193	(272)	(1,546)	(37)
Net change in unrealized gains on available-for-sale securities	5,802	2,887	9,226	6,066
Other comprehensive income	6,995	2,615	7,680	6,029
Comprehensive income	$ 151,788	$ 191,866	$ 290,904	$ 396,309