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]	Deferred Compensation DDFP [Member]	Common Stock Acquired By 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	37,056			37,056
Other comprehensive loss, net of tax	(14,273)				(14,273)
Cash dividends declared/paid	(16,527)			(16,527)
Distributions from DDFP	0							47	(47)
Purchases of treasury stock	(5,883)					(5,883)
Shares issued dividend reinvestment plan	595		(78)			673
Stock option exercises	153		(59)			212
Allocation of ESOP shares	1,258		(158)				1,416
Allocation of SAP shares	2,828		2,828
Allocation of stock options	141		141
Balance at Jun. 30, 2013	986,594	832	1,024,181	410,078	(6,557)	(391,268)	(50,672)	(7,251)	7,251
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	33,380			33,380
Other comprehensive loss, net of tax	9,537				9,537
Cash dividends declared/paid	(18,234)			(18,234)
Distributions from DDFP	0							46	(46)
Purchases of treasury stock	(3,880)					(3,880)
Treasury shares issued to finance acquisition	83,517		(962)			84,479
Shares issued dividend reinvestment plan	659		0			659
Stock option exercises	106		(22)			128
Allocation of ESOP shares	1,482		53				1,429
Allocation of SAP shares	3,919		3,919
Allocation of Treasury Shares	0		(4,253)			4,253
Allocation of stock options	152		152
Balance at Jun. 30, 2014	$ 1,121,391	$ 832	$ 1,025,031	$ 442,909	$ 4,686	$ (304,741)	$ (47,326)	$ (7,159)	$ 7,159