CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 203,865	$ 219,267	$ 176,712
Cash flow hedges:
Net unrealized gain (loss), net of tax of $0, $0, and ($5) in 2019, 2018, and 2017, respectively	0	0	4
Reclassification of net realized (gain) loss into current operations	0	0	(41)
Net change related to cash flow hedges	0	0	(37)
Available-for-sale investments:
Net unrealized gain (loss), net of tax of $515, ($188), and $2 in 2019, 2018, and 2017, respectively	5,219	(1,185)	703
Reclassification of net realized (gain) loss into current operations	(1,452)	(501)	(829)
Net change related to available-for-sale investments	3,767	(1,686)	(126)
Foreign currency translation adjustments:
Foreign currency translation adjustments	(541)	(4,216)	21,992
Net change related to foreign currency translation adjustments	(541)	(4,216)	21,992
Other comprehensive income (loss), net of tax	3,226	(5,902)	21,829
Total comprehensive income	$ 207,091	$ 213,365	$ 198,541