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			$ 21,509	$ 926,348	$ 737,922	$ (27,749)
Total stockholders' equity	$ 1,799,886	$ 36,104	21,509	926,348	807,293	4,360
Balance at beginning of period at Dec. 31, 2015			21,509	926,348	737,922	(27,749)
Common stock issued as 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 (loss) income	69,371				69,371
Dividends on preferred stock	0				0
Other comprehensive income, net of tax	32,109					32,109
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
Total stockholders' equity	1,786,243		21,745	931,856	830,928	(34,390)
Total stockholders' equity	1,786,243	36,104	21,745	931,856	830,928	(10,910)
Balance at beginning of period at Dec. 31, 2016	1,786,243		21,745	931,856	830,928	(34,390)
Common stock issued as compensation			43	(43)
Common stock withheld for taxes			(39)	(2,136)
Restricted stock grants			109	(109)
Restricted stock forfeited			(240)	240
Stock-based compensation				5,423
Net (loss) income	42,787				42,787
Dividends on preferred stock	(2,007)				(2,007)
Other comprehensive income, net of tax	23,480					23,480
Balance at end of period at Sep. 30, 2017	1,853,751	36,104	21,618	935,231	871,708	(10,910)
Total stockholders' equity	$ 1,853,751	$ 36,104	$ 21,618	$ 935,231	$ 871,708	$ (10,910)