Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in-Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss), net	Treasury Stock	Unearned ESOP Shares
Beginning balance at Dec. 31, 2010	$ 749,777	$ 105,515	$ 366,488	$ 291,492	$ (2,458)	$ (7,660)	$ (3,600)
Beginning balance, shares at Dec. 31, 2010		104,846,194
Net income	12,665			12,665
Other comprehensive income	4,967				4,967
Cash dividends declared	(6,278)			(6,278)
Net decrease in unearned ESOP shares	1,000						1,000
ESOP market value adjustment	(307)		(307)
Discount on dividend reinvestment plan purchases	(32)		(32)
Tax benefit of stock options exercised	6		6
Treasury stock acquired	(9)					(9)
Treasury stock acquired, shares		(1,336)
Treasury stock reissued	72		0	(83)		155
Treasury stock reissued, shares		13,760
Restricted stock	71	25	(10)	0		56
Restricted stock, shares		25,000
Common stock issuance	144	23	121			0
Common stock issuance, shares		23,376
Ending balance at Jun. 30, 2011	762,076	105,563	366,266	297,796	2,509	(7,458)	(2,600)
Ending balance, shares at Jun. 30, 2011		104,906,994
Beginning balance at Dec. 31, 2011	758,543	105,563	365,868	294,056	2,001	(7,345)	(1,600)
Beginning balance, shares at Dec. 31, 2011	104,916,994	104,916,994
Net income	23,372			23,372
Other comprehensive income	833				833
Cash dividends declared	(8,402)			(8,402)
Net decrease in unearned ESOP shares	1,000						1,000
ESOP market value adjustment	(310)		(310)
Discount on dividend reinvestment plan purchases	(42)		(42)
Tax benefit of stock options exercised	1		1
Treasury stock acquired	(3,045)					(3,045)
Treasury stock acquired, shares		(469,700)
Treasury stock reissued	354		0	(296)		650
Treasury stock reissued, shares		57,552
Restricted stock	186		24	(1,264)		1,426
Restricted stock, shares		224,000
Ending balance at Jun. 30, 2012	$ 772,490	$ 105,563	$ 365,541	$ 307,466	$ 2,834	$ (8,314)	$ (600)
Ending balance, shares at Jun. 30, 2012	104,728,846	104,728,846