Condensed 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
Before Tax Amount
Income (loss), before tax amount		$ 25,760	$ 1,821	$ 66,167	$ 2,053
Net unrealized gains (losses) on available-for-sale investment securities, before tax amount
Net unrealized holding gains arising during the period		788	7,169	2,982	2,204
Reversal of provision for credit losses		0	42	384	(555)
Less: reclassification adjustment for net gains on sales realized in net income	[1]	(54)	(65)	(119)	(760)
Other comprehensive income (loss), securities, available-for-sale, adjustment, before tax		734	7,062	2,479	1,999
Net unrealized gains (losses) on interest rate swaps used in cash flow hedges, before tax amount
Net unrealized holding losses arising during the period		(4)	(62)	2	(559)
Less: reclassification adjustment for net (gains) losses realized in net income	[2]	76	69	152	98
Other comprehensive income (loss), derivatives qualifying as hedges, before tax		72	7	154	(461)
Defined benefit pension plans, Before Tax Amount
Amortization of net actuarial loss included in net periodic pension costs	[3]	329	297	658	594
Total defined benefit pension plans		329	297	658	594
Other comprehensive income (loss), before tax amount		1,135	7,366	3,291	2,132
Total comprehensive income (loss), before tax amount		26,895	9,187	69,458	4,185
Tax Expense (Benefit)
Income tax expense (benefit)		4,885	(264)	12,689	(870)
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		167	1,504	628	462
Reversal of provision for credit losses		0	8	81	(117)
Less: reclassification adjustment for net gains on sales realized in net income	[1]	(11)	(14)	(25)	(160)
Total net unrealized gains on available-for-sale investment securities		156	1,482	522	419
Net unrealized gains (losses) on interest rate swaps used in cash flow hedges, tax expense (benefit)
Other comprehensive income (loss), unrealized gain (loss) on derivatives arising during period, tax		(1)	(13)	0	(118)
Less: reclassification adjustment for net (gains) losses realized in net income	[2]	16	14	32	21
Other comprehensive income (loss), derivatives qualifying as hedges, tax		15	1	32	(97)
Defined benefit pension plans, tax expense (benefit)
Amortization of net actuarial loss included in net periodic pension costs	[3]	69	62	138	124
Other comprehensive (income) loss, defined benefit plan, after reclassification adjustment, tax		69	62	138	124
Other comprehensive income (loss), tax expense (benefit)		240	1,545	692	446
Total comprehensive income (loss), tax expense (benefit)		5,125	1,281	13,381	(424)
Net of Tax Amount
Net income		20,875	2,085	53,478	2,923
Net unrealized gains (losses) on available-for-sale investment securities, net of tax amount
Net unrealized holding gains arising during the period		621	5,665	2,354	1,742
Reversal of provision for credit losses		0	34	303	(438)
Less: reclassification adjustment for net gains on sales realized in net income	[1]	(43)	(51)	(94)	(600)
Other comprehensive income (loss), securities, available-for-sale, adjustment, after tax		578	5,580	1,957	1,580
Net unrealized gains (losses) on interest rate swaps used in cash flow hedges, net of tax amount
Other comprehensive income (loss), unrealized gain (loss) on derivatives arising during period, net of tax		(3)	(49)	2	(441)
Less: reclassification adjustment for net (gains) losses realized in net income	[2]	60	55	120	77
Total net unrealized gains on interest rate swaps used in cash flow hedges		57	6	122	(364)
Defined benefit pension plans, net of tax amount
Amortization of net actuarial loss included in net periodic pension costs	[3]	260	235	520	470
Other comprehensive (income) loss, defined benefit plan, after reclassification adjustment, after tax		260	235	520	470
Other comprehensive income (loss), net of tax amount		895	5,821	2,599	1,686
Total comprehensive income (loss), net of tax amount		$ 21,770	$ 7,906	$ 56,077	$ 4,609

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

[2] (2) Included in interest expense on demand deposits on the 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.