Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (5,758)	$ 10,210	$ 19,808	$ 14,194
Available-for-sale investment securities:
Gross unrealized holding (loss) gain arising during the period	(7,685)	(2,974)	(16,738)	15,480
Related tax benefit (expense)	1,592	624	3,493	(3,251)
Reclassification adjustment for net loss (gain) included in net (loss) income	166	(2)	704	(383)
Related tax (benefit) expense	(44)	0	(157)	80
Net effect on other comprehensive (loss) income	(5,971)	(2,352)	(12,698)	11,926
Defined benefit plan:
Net gain (loss) arising during the period	1,818	533	(1,826)	1,054
Related tax (expense) benefit	(407)	(113)	408	(222)
Amortization of unrecognized gain and service cost on benefit plans	20	33	81	97
Related tax expense	(5)	(7)	(18)	(21)
Recognition of gain due to settlement and curtailment	143	531	143	1,050
Related tax expense	(32)	112	32	221
Net effect on other comprehensive income	1,537	25	1,592	73
Cash flow hedges:
Net gain (loss) arising during the period	858	803	4,800	(9,661)
Related tax (expense) benefit	(90)	(168)	(918)	2,029
Net effect on other comprehensive income (loss)	768	635	3,882	(7,632)
Total other comprehensive (loss) income, net of tax	(3,666)	(1,692)	(7,224)	4,367
Total comprehensive (loss) income	$ (9,424)	$ 8,518	$ 12,584	$ 18,561