Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net change in unrealized gains (losses), tax expense (benefit)	$ 12,585	$ 13,179	$ (2,223)
Reclassification adjustment for gains, tax expense	2,178	80	5
Amortization of unrealized gain on securities reclassified to held-to-maturity, tax expense	60	98	136
Change in unfunded pension liability related to unrealized (loss) gain, prior service cost and transition obligation, tax (benefit) expense	(585)	(1,439)	(10)
Pension settlement, tax	67	0	0
Net change in cash flow hedge, tax (benefit)	493	593	(29)
Amortization of unrealized gain on terminated cash flow hedges, tax expense	(106)	0	0
Equity method investment tax benefit	$ (3)	$ 0	$ 0