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	$ 16,344	$ 12,376	$ 27,870	$ 29,704
Unrealized gain on securities:
Unrealized holding gain arising during period	1,947	1,873	13,378	15,042
Less: reclassification adjustment for net gain included in net income			(15,712)	(1,295)
Income tax benefit (expense) related to items of other comprehensive income	(561)	(540)	673	(3,960)
Other comprehensive income (loss), net of tax	1,386	1,333	(1,661)	9,787
Comprehensive income	$ 17,730	$ 13,709	$ 26,209	$ 39,491