Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 111,096	$ 132,168	$ 321,404	$ 372,689
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	7,085	(5,207)	(5,051)	(4,687)
Unrealized (loss) gain on investments:
Unrealized (losses) gains during the period, net of income taxes of $154, $(27), $(218) and $(497)	(542)	71	702	1,633
Reclassification adjustment for losses realized in net income, net of income taxes of $(63), $(23), $(126) and $(73)	238	96	455	274
Unrealized gain on investments	(304)	167	1,157	1,907
Total other comprehensive income (loss), net of tax	6,781	(5,040)	(3,894)	(2,780)
Comprehensive income	$ 117,877	$ 127,128	$ 317,510	$ 369,909