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	$ 151,099	$ 135,413	$ 84,402
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities, net of tax	21	(4)	(2)
Comprehensive income	$ 151,120	$ 135,409	$ 84,400