Consolidated Statements Of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows From Operating Activities:
Net income	$ 21,426,000	$ 18,214,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	2,315,000	2,081,000
Credit for deferred income taxes	(3,502,000)	(348,000)
Depreciation and amortization	2,003,000	1,713,000
Premium amortization on investment securities, net	965,000	1,608,000
Net gains on sales of securities		(58,000)
Stock-based compensation expense	1,261,000	1,331,000
Common stock issued in lieu of cash for director fees	31,000	27,000
Accretion of cash surrender value on bank-owned life insurance	(1,025,000)	(745,000)
Net pension credit	(159,000)	(59,000)
Decrease (increase) in other assets	3,204,000	(676,000)
Increase (decrease) in accrued expenses and other liabilities	2,444,000	(501,000)
Net cash provided by operating activities	28,963,000	22,587,000
Proceeds from sales of investment securities:
Held-to-maturity		355,000
Available-for-sale		40,011,000
Proceeds from maturities and redemptions of investment securities:
Held-to-maturity	3,187,000	3,762,000
Available-for-sale	39,574,000	58,931,000
Purchases of investment securities:
Held-to-maturity	(1,098,000)	(1,883,000)
Available-for-sale	(137,126,000)	(19,462,000)
Net increase in loans	(304,524,000)	(228,637,000)
Proceeds from sale of other real estate owned	5,125,000
Net decease in restricted stock	655,000	1,233,000
Purchases of premises and equipment, net	(2,454,000)	(3,006,000)
Purchases of bank-owned life insurance	(20,000,000)	(25,000,000)
Net cash used in investing activities	(416,661,000)	(173,696,000)
Cash Flows From Financing Activities:
Net increase in deposits	411,901,000	206,891,000
Net decrease in short-term borrowings	(25,234,000)	(70,995,000)
Proceeds from long-term debt	39,680,000	42,050,000
Repayment of long-term debt	(48,950,000)	(8,900,000)
Proceeds from issuance of common stock, net	15,854,000	8,439,000
Proceeds from exercise of stock options	153,000	604,000
Shares withheld upon the vesting and conversion of RSUs	(733,000)	(527,000)
Cash dividends paid	(7,459,000)	(6,672,000)
Net cash provided by financing activities	385,212,000	170,890,000
Net increase (decrease) in cash and cash equivalents	(2,486,000)	19,781,000
Cash and cash equivalents, beginning of year	69,672,000	36,929,000
Cash and cash equivalents, end of period	67,186,000	56,710,000
Supplemental Cash Flow Disclosures:
Cash paid for interest	15,720,000	10,008,000
Cash paid for income taxes	365,000	5,933,000
Noncash investing and financing activities:
Cash dividends payable	$ 3,910,000	$ 3,449,000