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	$ 1,705,750	$ 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			8	(8)
Repurchase of common stock			(5)	(231)
Restricted stock grants			83	(83)
Restricted stock forefeited			(1)	1
Stock-based compensation				1,457
Net income (loss)	25,646				25,646
Other comprehensive income (loss), net of tax	7,140					7,140
Balance at end of period at Mar. 31, 2015	1,705,750	36,104	21,383	917,203	742,271	(11,211)
Total stockholders' equity	1,705,750	36,104	21,383	917,203	742,271	(11,211)
Total stockholders' equity	1,694,134		21,509	926,348	737,922	(27,749)
Total stockholders' equity	1,749,167	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			25	(25)
Repurchase of common stock			(12)	(247)
Restricted stock grants			179	(179)
Restricted stock forefeited			0	0
Stock-based compensation				1,557
Net income (loss)	23,344				23,344
Other comprehensive income (loss), net of tax	30,391					30,391
Balance at end of period at Mar. 31, 2016	1,749,167	36,104	21,701	927,454	761,266	2,642
Total stockholders' equity	$ 1,749,167	$ 36,104	$ 21,701	$ 927,454	$ 761,266	$ 2,642