Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total		Common Stock [Member]	Additional Paid-In Capital	Retained Earnings	Unallocated ESOP Shares	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Stockholders' Equity, Beginning Balance at Dec. 31, 2014		$ 200,926		$ 17,079	$ 239,721	$ 29,458	$ (1,450)	$ (7,166)	$ (76,716)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		18,093		0	0	18,093	0	0	0
Other Comprehensive Income		646	[1],[2]	0	0	0	0	646	0
Stock Issued During Period, Value, Stock Dividend		0		342	8,939	(9,281)	0	0	0
Cash Dividends Paid	[3]	(9,479)		0	0	(9,479)	0	0	0
Stock Options Exercised, Net		531		0	289	0	0	0	242
Shares Issued Under the Directors' Stock Plan		118		0	73	0	0	0	45
Shares Issued Under the Employee Stock Purchase Plan		359		0	222	0	0	0	137
Shares Issued for Dividend Reinvestment Plans		439		0	281	0	0	0	158
Stock-Based Compensation Expense		233		0	233	0	0	0	0
Tax Benefit for Disposition of Stock Options		31		0	31	0	0	0	0
Purchases of Treasury Stock		(1,247)		0	0	0	0	0	(1,247)
Allocation of ESOP Stock		492		0	142	0	350	0	0
Stockholders' Equity, Ending Balance at Sep. 30, 2015		211,142		17,421	249,931	28,791	(1,100)	(6,520)	(77,381)
Stockholders' Equity, Beginning Balance at Dec. 31, 2015		213,971		17,421	250,680	32,139	(1,100)	(7,972)	(77,197)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		19,934		0	0	19,934	0	0	0
Other Comprehensive Income		2,530	[1],[2]	0	0	0	0	2,530	0
Stock Issued During Period, Value, Stock Dividend		0		522	16,415	(16,937)	0	0	0
Cash Dividends Paid		(9,736)		0	0	(9,736)	0	0	0
Stock Options Exercised, Net		1,775		0	980	0	0	0	795
Shares Issued Under the Directors' Stock Plan		112		0	76	0	0	0	36
Shares Issued Under the Employee Stock Purchase Plan		(358)		0	(229)	0	0	0	(129)
Shares Issued for Dividend Reinvestment Plans		1,302		0	862	0	0	0	440
Stock-Based Compensation Expense		215		0	215	0	0	0	0
Tax Benefit for Disposition of Stock Options		63		0	63	0	0	0	0
Purchases of Treasury Stock		(1,826)		0	0	0	0	0	(1,826)
Allocation of ESOP Stock		510		0	160	0	350	0	0
Stockholders' Equity, Ending Balance at Sep. 30, 2016		$ 229,208		$ 17,943	$ 269,680	$ 25,400	$ (750)	$ (5,442)	$ (77,623)

[1] All amounts are net of tax. Amounts in parentheses indicate debits.

[2] These accumulated other comprehensive income components are included in the computation of net periodic pension cost.

[3] Share and Per Share Amounts have been restated for the September 29, 2016 3% stock dividend.