CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash Flows From Operating Activities:
Net income	$ 6,805,000	$ 5,781,000	$ 20,902,000	$ 18,765,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			9,340,000	8,391,000
Gains on sales of securities			(44,000)	(1,069,000)
Stock-based compensation expense	1,066,000	799,000	2,585,000	2,277,000
Provision for (release of) credit losses / loan losses	340,000	0	(870,000)	725,000
Decrease in deferred income tax asset			22,000	1,000
Increase in current income tax liability			79,000	527,000
(Decrease) increase in pension liability			(1,252,000)	3,315,000
(Increase) decrease in accounts receivable			(628,000)	1,339,000
Other operating activities, net			546,000	5,790,000
Net cash provided by operating activities			30,680,000	40,061,000
Cash Flows From Investing Activities:
Proceeds from sales of securities available-for-sale	30,074,000	0	43,190,000	19,629,000
Proceeds from maturities of securities available-for-sale			83,265,000	43,605,000
Purchase of securities available-for-sale			(322,336,000)	(2,931,000)
Net decrease (increase) in loans			19,229,000	(171,902,000)
Purchase of bank-owned life insurance			(24,868,000)	0
(Increase) decrease in payments in excess of funding			(71,816,000)	44,766,000
Purchases of premises and equipment, net			(2,697,000)	(1,705,000)
Net cash used in investing activities			(276,033,000)	(68,538,000)
Cash Flows From Financing Activities:
Net (decrease) increase in noninterest-bearing demand deposits			(26,184,000)	23,290,000
Net increase in interest-bearing demand and savings deposits			67,930,000	136,639,000
Net decrease in time deposits			(5,285,000)	(5,881,000)
Net increase in accounts and drafts payable			70,099,000	146,280,000
Net decrease in short-term borrowings			0	(18,000,000)
Cash dividends paid			(11,576,000)	(11,704,000)
Purchase of common shares for treasury			(18,975,000)	(5,508,000)
Other financing activities, net			(875,000)	(1,142,000)
Net cash provided by financing activities			75,134,000	263,974,000
Net (decrease) increase in cash and cash equivalents			(170,219,000)	235,497,000
Cash and cash equivalents at beginning of period			670,528,000	203,954,000	$ 203,954,000
Cash and cash equivalents at end of period	$ 500,309,000	$ 439,451,000	500,309,000	439,451,000	$ 670,528,000
Supplemental information:
Cash paid for interest			885,000	1,889,000
Cash paid for income taxes			$ 4,176,000	$ 3,567,000