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	$ 9,163	$ 18,034	$ 17,221	$ 19,082
Other comprehensive income (loss):
Unrealized holding gain (loss) on securities available-for-sale	3,371	551	(2,960)	1,965
Income tax effect	(790)	(149)	693	(531)
Reclassification adjustment for gain recognized in income	(1,708)	(554)	(2,851)	(830)
Income tax effect	400	150	668	225
Change in defined benefit pension plan	321	(1,001)	2,026	(1,707)
Income tax effect	(75)	270	(474)	461
Reclassification adjustment for amortization of net actuarial loss recognized in income	127	105	254	210
Income tax effect	(30)	(28)	(60)	(57)
Reclassification adjustment for carrying value adjustment - investment hedge recognized in income	359	960	623	(833)
Income tax effect	(84)	(259)	(146)	225
Total other comprehensive income (loss)	1,891	45	(2,227)	(872)
Comprehensive loss attributable to noncontrolling interest	84	0	111	0
Comprehensive income	$ 11,138	$ 18,079	$ 15,105	$ 18,210