Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Before Tax Amount
Income (loss) before tax amount		$ 25,168	$ 40,407
Net unrealized gains (losses) on available-for-sale investment securities, before tax amount
Net unrealized holding (losses) gains arising during the period		(20,369)	2,194
Provision (reversal of provision) for credit losses		(346)	384
Less: reclassification adjustment for net gains on sales realized in net income	[1]	(30)	(65)
Other comprehensive income (loss), securities, available-for-sale, adjustment, before tax		(20,053)	1,745
Net unrealized gains (losses) on interest rate swaps used in cash flow hedges, before tax amount
Net unrealized holding gains arising during the period		76	6
Less: reclassification adjustment for net losses realized in net income (2)	[2]	68	76
Total net unrealized gains on interest rate swaps used in cash flow hedges		144	82
Defined benefit pension plans, Before Tax Amount
Amortization of net actuarial loss included in net periodic pension costs	[3]	218	329
Total defined benefit pension plans		218	329
Other comprehensive income (loss), before tax amount		(19,691)	2,156
Total comprehensive income (loss), before tax amount		5,477	42,563
Tax Expense (Benefit)
Income tax expense		4,851	7,804
Net unrealized gains (losses) on available-for-sale investment securities, tax expense (benefit)
Other comprehensive income (loss), securities, available-for-sale, unrealized holding gain (loss) arising during period, tax		(4,278)	461
Provision (reversal of provision) for credit losses		(73)	81
Less: reclassification adjustment for net gains on sales realized in net income	[1]	(6)	(14)
Total net unrealized (losses) gains on available-for-sale investment securities		(4,211)	366
Net unrealized gains (losses) on interest rate swaps used in cash flow hedges, tax expense (benefit)
Net unrealized holding gains arising during the period		16	1
Less: reclassification adjustment for net losses realized in net income (2)	[2]	14	16
Total net unrealized gains on interest rate swaps used in cash flow hedges		30	17
Defined benefit pension plans, tax expense (benefit)
Amortization of net actuarial loss included in net periodic pension costs	[3]	46	69
Other comprehensive (income) loss, defined benefit plan, after reclassification adjustment, tax		46	69
Other comprehensive income (loss), tax expense (benefit)		(4,135)	452
Total comprehensive income (loss), tax expense (benefit)		716	8,256
Net of Tax Amount
Net income		20,317	32,603
Net unrealized gains (losses) on available-for-sale investment securities, net of tax amount
Net unrealized holding (losses) gains arising during the period		(16,091)	1,733
Provision (reversal of provision) for credit losses		(273)	303
Less: reclassification adjustment for net gains on sales realized in net income	[1]	(24)	(51)
Other comprehensive income (loss), securities, available-for-sale, adjustment, after tax		(15,842)	1,379
Net unrealized gains (losses) on interest rate swaps used in cash flow hedges, net of tax amount
Net unrealized holding gains arising during the period		60	5
Less: reclassification adjustment for net losses realized in net income (2)	[2]	54	60
Total net unrealized gains on interest rate swaps used in cash flow hedges		114	65
Defined benefit pension plans, net of tax amount
Amortization of net actuarial loss included in net periodic pension costs	[3]	172	260
Other comprehensive (income) loss, defined benefit plan, after reclassification adjustment, after tax		172	260
Other comprehensive income (loss), net of tax amount		(15,556)	1,704
Total comprehensive income (loss), net of tax amount		$ 4,761	$ 34,307

[1] (1) Included in net gain on sales of investment securities on the condensed consolidated statements of income (before tax amount).

[2] (2) Included in interest expense on demand deposits on the condensed consolidated statements of income (before tax amount).

[3] (3) These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (before tax amount). See Note 8, "Retirement Plans and Other Postretirement Benefits" for additional details. Note: See accompanying notes to the unaudited condensed consolidated financial statements.