Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Unallocated ESOP Shares [Member]	Common Stock Acquired By DDFP [Member]	Deferred Compensation DDFP [Member]
Balance at Dec. 31, 2012	$ 981,246	$ 832	$ 1,021,507	$ 389,549	$ 7,716	$ (386,270)	$ (52,088)	$ (7,298)	$ 7,298
Net income	17,828			17,828
Other comprehensive income, net of tax	(1,663)				(1,663)
Cash dividends paid	(8,086)			(8,086)
Distributions from DDFP	0							23	(23)
Purchases of treasury stock	(839)					(839)
Shares issued dividend reinvestment plan	301		(44)			345
Stock option exercises	18		(9)			27
Allocation of ESOP shares	627		(81)				708
Allocation of SAP shares	942		942
Allocation of stock options	71		71
Balance at Mar. 31, 2013	990,445	832	1,022,386	399,291	6,053	(386,737)	(51,380)	(7,275)	7,275
Balance at Dec. 31, 2013	1,010,753	832	1,026,144	427,763	(4,851)	(390,380)	(48,755)	(7,205)	7,205
Net income	17,029			17,029
Other comprehensive income, net of tax	3,878				3,878
Cash dividends paid	(9,190)			(9,190)
Distributions from DDFP	0							23	(23)
Purchases of treasury stock	(3,881)					(3,881)
Shares issued dividend reinvestment plan	334					334
Stock option exercises	0		0			0
Allocation of ESOP shares	756		42				714
Allocation of SAP shares	1,583		1,583
Transfer of treasury shares to SAP	0		(4,253)			4,253
Allocation of stock options	79		79
Balance at Mar. 31, 2014	$ 1,021,341	$ 832	$ 1,023,595	$ 435,602	$ (973)	$ (389,674)	$ (48,041)	$ (7,182)	$ 7,182