CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows From Operating Activities:
Net income	$ 24,348	$ 23,056	$ 24,033
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,429	8,859	8,181
Net gains on sales of securities	(387)	(2,910)	(23)
Stock-based compensation expense	1,959	2,059	2,041
Provisions for loan losses	(1,500)	(850)
Deferred income tax expense (benefit)	319	(137)	(621)
Increase (decrease) in income tax liability	357	47	(24)
Increase in pension liability	4,137	4,550	2,282
Other operating activities, net	(3,473)	(1,181)	(1,026)
Net cash provided by operating activities	35,189	33,493	34,843
Cash Flows From Investing Activities:
Proceeds from sales of securities available-for-sale	21,491	99,347	587
Proceeds from maturities of securities available-for-sale	43,524	38,460	18,340
Purchase of securities available-for-sale	(96,290)	(161,279)	(54,054)
Net (increase) decrease in loans	(5,771)	10,882	(16,954)
Decrease (increase) in payments in excess of funding	179	14,701	(42,577)
Purchases of premises and equipment, net	(4,684)	(5,747)	(6,291)
Net cash used in investing activities	(41,551)	(3,636)	(100,949)
Cash Flows From Financing Activities:
Net increase in noninterest-bearing demand deposits	32,833	22,824	15,158
Net (decrease) increase in interest-bearing demand and savings deposits	(51,440)	23,536	39,766
Net decrease in time deposits	(5,916)	(18,075)	(19,221)
Net increase (decrease) in accounts and drafts payable	65,028	(78,169)	111,475
Cash dividends paid	(9,979)	(9,697)	(9,337)
Purchase of common shares for treasury	(9,215)	(10,951)	(1,848)
Other financing activities, net	(1,378)	(488)	(814)
Net cash provided by (used in) financing activities	19,933	(71,020)	135,179
Net increase (decrease) in cash and cash equivalents	13,571	(41,163)	69,073
Cash and cash equivalents at beginning of year	253,172	294,335	225,262
Cash and cash equivalents at end of year	266,743	253,172	294,335
Supplemental information:
Cash paid for interest	2,017	2,133	2,491
Cash paid for income taxes	$ 7,061	$ 8,190	$ 8,476