Consolidated Statements Of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash Flows From Operating Activities:
Net income	$ 18,214,000	$ 15,364,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	2,081,000	392,000
Provision (credit) for deferred income taxes	(348,000)	594,000
Depreciation and amortization	1,713,000	1,590,000
Premium amortization on investment securities, net	1,608,000	1,880,000
Net gains on sales of securities	(58,000)	(1,844,000)
Net loss on sales of loans held-for-sale		5,000
Loss on debt extinguishment		1,756,000
Stock-based compensation expense	1,331,000	914,000
Common stock issued in lieu of cash for director fees	27,000
Accretion of cash surrender value on bank-owned life insurance	(745,000)	(467,000)
Pension expense (credit)	(59,000)	9,000
Increase in other assets	(676,000)	(2,098,000)
Decrease in accrued expenses and other liabilities	(501,000)	(3,138,000)
Net cash provided by operating activities	22,587,000	14,957,000
Proceeds From Sales Of Investment Securities [Abstract]
Held-to-maturity	355,000	123,000
Available-for-sale	40,011,000	40,989,000
Proceeds from maturities and redemptions of investment securities:
Held-to-maturity	3,762,000	3,384,000
Available-for-sale	58,931,000	48,646,000
Purchases of investment securities
Held-to-maturity	(1,883,000)	(1,287,000)
Available-for-sale	(19,462,000)	(203,374,000)
Proceeds from sales of loans held-for-sale		100,000
Net increase in loans	(228,637,000)	(105,400,000)
Net decrease in restricted stock	1,233,000	5,361,000
Purchases of premises and equipment, net	(3,006,000)	(2,787,000)
Purchase of bank-owned life insurance	(25,000,000)
Net cash used in investing activities	(173,696,000)	(214,245,000)
Cash Flows From Financing Activities:
Net increase in deposits	206,891,000	340,180,000
Net decrease in short-term borrowings	(70,995,000)	(153,836,000)
Proceeds from long-term debt	42,050,000	23,500,000
Repayments of long-term debt	(8,900,000)	(31,756,000)
Proceeds from issuance of common stock, net	8,439,000	38,161,000
Proceeds from exercise of stock options	604,000	470,000
Repurchase and retirement of common stock	(527,000)	(370,000)
Cash dividends paid	(6,672,000)	(5,670,000)
Net cash provided by financing activities	170,890,000	210,679,000
Net increase in cash and cash equivalents	19,781,000	11,391,000
Cash and cash equivalents, beginning of year	36,929,000	39,635,000
Cash and cash equivalents, end of period	56,710,000	51,026,000
Cash paid for:
Interest	10,008,000	12,048,000
Income taxes	5,933,000	4,857,000
Noncash investing and financing activities:
Cash dividends payable	$ 3,449,000	$ 3,144,000