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 Income And Comprehensive Income [Abstract]
Net income	$ 23,353	$ 21,386	$ 58,101	$ 58,676
Other comprehensive income:
Unrealized gain on debt securities, net of tax	734	2,475	7,701	13,447
Comprehensive income	$ 24,087	$ 23,861	$ 65,802	$ 72,123