Consolidated Statement 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 beginning of period at Dec. 31, 2012	$ 981,246	$ 832	$ 1,021,507	$ 389,549	$ 7,716	$ (386,270)	$ (52,088)	$ (7,298)	$ 7,298
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	70,534			70,534
Other comprehensive loss, net of tax	(12,567)				(12,567)
Cash dividends paid	(32,320)			(32,320)
Distributions from DDFP	0		0					93	(93)
Purchases of treasury stock	(5,899)					(5,899)
Shares issued dividend reinvestment plan	1,244		(57)			1,301
Option exercises	354		(134)			488
Allocation of ESOP shares	3,318		(15)				3,333
Allocation of SAP shares	4,546		4,546
Allocation of stock options	297		297
Balance at end of period at Dec. 31, 2013	1,010,753	832	1,026,144	427,763	(4,851)	(390,380)	(48,755)	(7,205)	7,205
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	73,631			73,631
Other comprehensive loss, net of tax	4,880				4,880
Cash dividends paid	(36,118)			(36,118)
Distributions from DDFP	0							92	(92)
Purchases of treasury stock	(4,420)					(4,420)
Treasury shares issued - Team Capital Acquisition	83,517		(962)			84,479
Shares issued dividend reinvestment plan	1,336		0			1,336
Option exercises	117		(49)			166
Allocation of ESOP shares	3,550		107				3,443
Allocation of SAP shares	6,555		6,555
Reclassification of Stock awards			(32,787)			32,787
Allocation of Treasury Shares			(4,253)			4,253
Allocation of stock options	298		298
Balance at end of period at Dec. 31, 2014	1,144,099	832	995,053	465,276	29	(271,779)	(45,312)	(7,113)	7,113
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	83,722			83,722
Other comprehensive loss, net of tax	(2,575)				(2,575)
Cash dividends paid	(41,285)			(41,285)
Distributions from DDFP	85		85					596	(596)
Purchases of treasury stock	(1,988)					(1,988)
Shares issued dividend reinvestment plan	1,447		143			1,304
Option exercises	3,166		(283)			3,449
Allocation of ESOP shares	4,049		467				3,582
Allocation of SAP shares	5,073		5,073
Allocation of stock options	272		272
Balance at end of period at Dec. 31, 2015	$ 1,196,065	$ 832	$ 1,000,810	$ 507,713	$ (2,546)	$ (269,014)	$ (41,730)	$ (6,517)	$ 6,517