Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total		Common Stock	Additional Paid-In Capital	Retained Earnings		Unallocated ESOP Shares	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
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	13,196				13,196
Other Comprehensive Income	3,230	[1]						3,230
Cash Dividends Paid	(6,483)				(6,483)	[2]
Stock Options Exercised, Net	1,321			732					589
Shares Issued Under the Directors' Stock Plan	104			69					35
Shares Issued Under the Employee Stock Purchase Plan	250			157					93
Shares Issued for Dividend Reinvestment Plans	874			565					309
Stock-Based Compensation Expense	145			145
Tax Benefit for Disposition of Stock Options	46			46
Purchases of Treasury Stock	(1,648)								(1,648)
Allocation of ESOP Stock	367			117			250
Stockholders' Equity, Ending Balance at Jun. 30, 2016	225,373		17,421	252,511	38,852		(850)	(4,742)	(77,819)
Stockholders' Equity, Beginning Balance at Dec. 31, 2016	232,852		17,943	270,880	28,644		(400)	(6,834)	(77,381)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	13,839				13,839
Other Comprehensive Income	634	[1]						634
Cash Dividends Paid	(6,744)				(6,744)
Stock Options Exercised, Net	701			322					379
Shares Issued Under the Directors' Stock Plan	127			84					43
Shares Issued Under the Employee Stock Purchase Plan	242			160					82
Shares Issued for Dividend Reinvestment Plans	845			569					276
Stock-Based Compensation Expense	172			172
Purchases of Treasury Stock	(1,916)								(1,916)
Stockholders' Equity, Ending Balance at Jun. 30, 2017	$ 240,752		$ 17,943	$ 272,187	$ 35,739		$ (400)	$ (6,200)	$ (78,517)

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

[2] Cash dividends paid per share have been adjusted for the September 29, 2016 3.0% stock dividend.