Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 8,936	$ 7,553	$ 9,483	$ 14,291
Change in unrealized gain (loss) on investments:
Net unrealized gains (losses) arising during the period	3,280	1,626	(191)	4,330
Credit losses charged to income	87	0	526	0
Call and repayment (gains) losses charged to investment income	(150)	1	(216)	1
Reclassification adjustment for net realized gains	(1,427)	0	(1,154)	(33)
Net change in unrealized gains (losses)	1,790	1,627	(1,035)	4,298
Deferred income taxes on above change	(440)	(413)	253	(1,090)
Total other comprehensive income (loss), net of income taxes	1,350	1,214	(782)	3,208
Comprehensive income	$ 10,286	$ 8,767	$ 8,701	$ 17,499