CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Total stockholders' equity			$ 21,298	$ 916,067	$ 716,625	$ (18,351)
Total stockholders' equity	$ 1,700,950	$ 36,104	21,298	916,067	716,625	(18,351)
Balance at beginning of period at Dec. 31, 2014			21,298	916,067	716,625	(18,351)
Common stock issued for compensation			33	(33)
Common stock withheld for taxes			(18)	(949)
Restricted stock grants			102	(102)
Restricted stock forfeited			(2)	2
Stock-based compensation				4,535
Net income	6,330				6,330
Other comprehensive income (loss), net of tax	13,681					13,681
Common stock issued in exchange for trust preferred securities			85	5,543
Balance at end of period at Sep. 30, 2015	1,700,950	36,104	21,498	925,063	722,955	(4,670)
Total stockholders' equity	1,700,950	36,104	21,498	925,063	722,955	(4,670)
Total stockholders' equity	1,694,134		21,509	926,348	737,922	(27,749)
Total stockholders' equity	1,799,886	36,104	21,509	926,348	737,922	(27,749)
Balance at beginning of period at Dec. 31, 2015	1,694,134		21,509	926,348	737,922	(27,749)
Common stock issued for compensation			63	(63)
Common stock withheld for taxes			(26)	(834)
Restricted stock grants			193	(193)
Restricted stock forfeited			0	0
Stock-based compensation				5,132
Net income	69,371				69,371
Other comprehensive income (loss), net of tax	32,109					32,109
Common stock issued in exchange for trust preferred securities			0	0
Balance at end of period at Sep. 30, 2016	1,799,886	36,104	21,739	930,390	807,293	4,360
Total stockholders' equity	$ 1,799,886	$ 36,104	$ 21,739	$ 930,390	$ 807,293	$ 4,360