CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Unearned ESOP Shares [Member]	Treasury Stock [Member]	Maximum Cash Obligation Related To ESOP Shares [Member]
Beginning Balance at Dec. 31, 2011	$ 208,429	$ 41,467	$ 207,790	$ 4,974	$ (2,017)	$ (15,959)	$ (27,826)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 12,512, 8,964, and 12,825 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	647	647	0	0	0	0	0
Issuance of 2,092, 2,072, and 375 shares of common stock under the employee stock purchase plan for the years ending 2014, 2013, and 2012, respectfully	25	25	0	0	0	0	0
Forfeiture of 571, 525, and 718 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	(41)	(41)	0	0	0	0	0
Share-based compensation	20	20	0	0	0	0	0
Income tax benefit related to share-based compensation	92	92	0	0	0	0	0
Change related to ESOP shares	(2,889)	0	0	0	0	0	(2,889)
Release of 8,002, 8,360, and 8,724 shares of common stock under the employee stock ownership plan for the years ending 2014, 2013, and 2012, respectfully	535	31	0	0	504	0	0
Net income	26,833		26,833	0	0	0	0
Cash dividends ($1.15, $1.10, and $1.05 per share) for the years ending 2014, 2013, and 2012, respectfully	(4,998)	0	(4,998)	0	0	0	0
Purchase of 51,442, 19,204, and 35,892 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	(2,438)	0	0	0	0	(2,438)	0
Other comprehensive income (loss)	(1,019)	0	0	(1,019)	0	0	0
Ending Balance at Dec. 31, 2012	225,196	42,241	229,625	3,955	(1,513)	(18,397)	(30,715)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 12,512, 8,964, and 12,825 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	443	443	0	0	0	0	0
Issuance of 2,092, 2,072, and 375 shares of common stock under the employee stock purchase plan for the years ending 2014, 2013, and 2012, respectfully	146	146	0	0	0	0	0
Unearned restricted stock compensation	(800)	(800)	0	0	0	0	0
Forfeiture of 571, 525, and 718 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	(35)	(35)	0	0	0	0	0
Share-based compensation	28	28	0	0	0	0	0
Income tax benefit related to share-based compensation	92	92	0	0	0	0	0
Change related to ESOP shares	1,141	0	0	0	0	0	1,141
Release of 8,002, 8,360, and 8,724 shares of common stock under the employee stock ownership plan for the years ending 2014, 2013, and 2012, respectfully	584	79	0	0	505	0	0
Net income	25,931	0	25,931	0	0	0	0
Cash dividends ($1.15, $1.10, and $1.05 per share) for the years ending 2014, 2013, and 2012, respectfully	(5,186)	0	(5,186)	0	0	0	0
Purchase of 51,442, 19,204, and 35,892 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	(1,387)	0	0	0	0	(1,387)	0
Other comprehensive income (loss)	(2,364)	0	0	(2,364)	0	0	0
Ending Balance at Dec. 31, 2013	243,789	42,194	250,370	1,591	(1,008)	(19,784)	(29,574)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 12,512, 8,964, and 12,825 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	862	862	0	0	0	0	0
Issuance of 2,092, 2,072, and 375 shares of common stock under the employee stock purchase plan for the years ending 2014, 2013, and 2012, respectfully	158	158	0	0	0	0	0
Unearned restricted stock compensation	(464)	(464)	0	0	0	0	0
Forfeiture of 571, 525, and 718 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	(40)	(40)	0	0	0	0	0
Share-based compensation	29	29	0	0	0	0	0
Income tax benefit related to share-based compensation	60	60	0	0	0	0	0
Change related to ESOP shares	(4,997)	0	0	0	0	0	(4,997)
Release of 8,002, 8,360, and 8,724 shares of common stock under the employee stock ownership plan for the years ending 2014, 2013, and 2012, respectfully	630	126	0	0	504	0	0
Net income	26,974	0	26,974	0	0	0	0
Cash dividends ($1.15, $1.10, and $1.05 per share) for the years ending 2014, 2013, and 2012, respectfully	(5,420)	0	(5,420)	0	0	0	0
Purchase of 51,442, 19,204, and 35,892 shares of common stock for the years ending 2014, 2013, and 2012, respectfully	(4,014)	0	0	0	0	(4,014)	0
Other comprehensive income (loss)	(2,039)	0	0	(2,039)	0	0	0
Ending Balance at Dec. 31, 2014	$ 255,528	$ 42,925	$ 271,924	$ (448)	$ (504)	$ (23,798)	$ (34,571)