Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities:
Net Income	$ 29,326	$ 26,534	$ 24,662
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Provision for Loan Losses	2,736	2,033	1,347
Depreciation and Amortization	5,398	5,940	6,293
Allocation of ESOP Stock	353	1,122	495
Gains on the Sale of Securities Available-for-Sale	(134)	(317)	(172)
Losses on the Sale of Securities Available-for-Sale	582	339	43
Loans Originated and Held-for-Sale	(17,468)	(23,787)	(20,731)
Proceeds from the Sale of Loans Held-for-Sale	18,171	24,422	21,524
Net Gains on the Sale of Loans	(546)	(821)	(692)
Net Losses on the Sale or Write-down of Premises and Equipment, Other Real Estate Owned and Repossessed Assets	210	232	297
Net Gain on the Sale of a Subsidiary	0	0	(204)
Contributions to Pension & Postretirement Plans	(792)	(690)	(3,858)
Deferred Income Tax (Benefit) Expense	(1,530)	(283)	1,036
Shares Issued Under the Directors’ Stock Plan	233	205	227
Stock-Based Compensation Expense	351	287	308
Tax Benefit from Exercise of Stock Options	112	0	0
Net (Increase) in Other Assets	(157)	(1,598)	(1,147)
Net Increase (Decrease) in Other Liabilities	982	1,077	(502)
Net Cash Provided By Operating Activities	37,827	34,695	28,926
Cash Flows from Investing Activities:
Proceeds from the Sale of Securities Available-for-Sale	107,175	97,930	66,551
Proceeds from the Maturities and Calls of Securities Available-for-Sale	53,863	88,719	93,817
Purchases of Securities Available-for-Sale	(117,262)	(134,950)	(201,820)
Proceeds from the Maturities and Calls of Securities Held-to-Maturity	49,244	56,461	48,409
Purchases of Securities Held-to-Maturity	(40,851)	(82,433)	(68,210)
Net Increase in Loans	(200,600)	(182,065)	(164,710)
Proceeds from the Sales or Write-down of Premises and Equipment, Other Real Estate Owned and Repossessed Assets	1,408	1,991	1,901
Purchase of Premises and Equipment	(2,602)	(1,441)	(1,621)
Proceeds from the Sale of a Subsidiary, Net	96	72	132
Net (Increase) Decrease in Federal Home Loan Bank Stock	963	(2,073)	(3,988)
Purchase of Bank Owned Life Insurance	0	0	0
Net Cash Used In Investing Activities	(148,566)	(157,789)	(229,539)
Cash Flows from Financing Activities:
Net Increase in Deposits	128,569	86,123	127,475
Net Increase (Decrease) in Short-Term Federal Home Loan Bank Borrowings	(18,000)	41,000	41,000
Net Increase in Short-Term Borrowings	29,130	12,663	3,752
Federal Home Loan Bank Advances	0	0	55,000
Repayments of Federal Home Loan Bank Advances	0	0	(10,000)
Purchase of Treasury Stock	(3,248)	(2,141)	(1,498)
Shares Issued for Stock Option Exercises, net	1,190	2,404	918
Shares Issued Under the Employee Stock Purchase Plan	496	493	494
Tax Benefit for Exercises of Stock Options	0	188	59
Shares Issued for Dividend Reinvestment Plans	1,684	1,743	886
Cash Dividends Paid	(13,599)	(13,092)	(12,700)
Net Cash Provided By Financing Activities	126,222	129,381	205,386
Net Increase (Decrease) in Cash and Cash Equivalents	15,483	6,287	4,773
Cash and Cash Equivalents at Beginning of Year	57,355	51,068	46,295
Cash and Cash Equivalents at End of Year	72,838	57,355	51,068
Supplemental Disclosures to Statements of Cash Flow Information:
Interest on Deposits and Borrowings	6,957	5,341	4,856
Income Taxes	11,454	11,961	9,357
Non-cash Investing and Financing Activity:
Transfer of Loans to Other Real Estate Owned and Repossessed Assets	$ 1,779	$ 1,876	$ 3,046