Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 10,103	$ 4,749	$ 25,566	$ 3,984
Available-for-sale investment securities:
Gross unrealized holding gain (loss) arising during the period	3,525	(3,814)	(9,053)	18,454
Related tax (expense) benefit	(741)	801	1,901	(3,875)
Reclassification adjustment for net loss (gain) included in net income	202	(62)	538	(381)
Related tax (benefit) expense	(42)	13	(113)	80
Net effect on other comprehensive income (loss)	2,944	(3,062)	(6,727)	14,278
Defined benefit plan:
Net gain (loss) arising during the period	3	(156)	8	(521)
Related tax benefit (expense)	0	33	(1)	109
Amortization of unrecognized gain and service cost on benefit plans	31	36	61	64
Related tax expense	(6)	(8)	(13)	(14)
Recognition of gain due to settlement and curtailment	0	151	0	519
Related tax expense	0	(32)	0	(109)
Net effect on other comprehensive income	28	24	55	48
Cash flow hedges:
Net (loss) gain arising during the period	(294)	(734)	3,942	(10,464)
Related tax benefit (expense)	62	154	(828)	2,197
Net effect on other comprehensive (loss) income	(232)	(580)	3,114	(8,267)
Total other comprehensive income (loss), net of tax	2,740	(3,618)	(3,558)	6,059
Total comprehensive income	$ 12,843	$ 1,131	$ 22,008	$ 10,043