CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands	Total USD ($)	Common Stock [Member]	Preferred Stock [Member] USD ($)	Common Stock Including Additional Paid in Capital [Member] USD ($)	Retained Earnings (Accumulated Deficit) [Member] USD ($)	Accumulated Other Comprehensive Income (Loss) [Member] USD ($)	Unearned Restricted ESOP Shares [Member] USD ($)
Balance, beginning of the period at Dec. 31, 2011	$ 532,450		$ 120,702	$ 531,149	$ (119,465)	$ 2,051	$ (1,987)
Balance, beginning of the period, shares at Dec. 31, 2011		(17,553)
Net income	64,882				64,882
Other comprehensive income (loss)	50					50
Accretion of preferred stock discount	0		3,298		(3,298)
Repurchase of preferred stock	(124,000)		(124,000)
Gain on repurchase of preferred stock	2,471				2,471
Accrual of dividends on preferred stock	(4,938)				(4,938)
Accrual of dividends on common stock	(754)				(754)
Redemption of unallocated shares upon termination of ESOP, shares		0
Repurchase of shares upon termination of ESOP, shares		0
Issuance of common stock for stockholder reinvestment program, shares		1,815
Proceeds from issuance of common stock for stockholder reinvestment program, net of registration expenses amount	36,317			36,317
Issuance of unvested restricted common stock, net, shares		87
Amortization of share-based compensation related to restricted stock grants, net of shares surrendered	434			434
Amortization of compensation related to stock options	7			7
Net number of shares issued during the period		1,902
Balance, end of the period at Dec. 31, 2012	506,919		0	567,907	(61,102)	2,101	(1,987)
Balance, end of the period, shares at Dec. 31, 2012	(19,421)	(19,455)					(34)
Net income	46,555				46,555
Other comprehensive income (loss)	(5,097)					(5,097)
Gain on repurchase of preferred stock	0
Accrual of dividends on preferred stock	0
Accrual of dividends on common stock	(10,526)				(10,526)
Redemption of unallocated shares upon termination of ESOP, shares		0
Repurchase of shares upon termination of ESOP, shares		0
Issuance of common stock for stockholder reinvestment program, shares		2
Proceeds from issuance of common stock for stockholder reinvestment program, net of registration expenses amount	72			72
Issuance of unvested restricted common stock, net, shares		86
Amortization of share-based compensation related to restricted stock grants, net of shares surrendered	1,049			1,049
Net number of shares issued during the period		88
Balance, end of the period at Dec. 31, 2013	538,972		0	569,028	(25,073)	(2,996)	(1,987)
Balance, end of the period, shares at Dec. 31, 2013	(19,509)	(19,543)					(34)
Net income	54,165				54,165
Other comprehensive income (loss)	2,738					2,738
Gain on repurchase of preferred stock	0
Accrual of dividends on preferred stock	0
Accrual of dividends on common stock	(14,092)				(14,092)
Redemption of unallocated shares upon termination of ESOP, shares		(34)
Redemption of unallocated shares upon termination of ESOP	0			(1,987)			1,987
Repurchase of shares upon termination of ESOP, shares		(14)
Repurchase of shares upon termination of ESOP	(555)			(555)
Issuance of common stock for stockholder reinvestment program, shares		3
Proceeds from issuance of common stock for stockholder reinvestment program, net of registration expenses amount	127			127
Issuance of unvested restricted common stock, net, shares		73
Amortization of share-based compensation related to restricted stock grants, net of shares surrendered	2,269			2,269
Net number of shares issued during the period		28
Balance, end of the period at Dec. 31, 2014	$ 583,624		$ 0	$ 568,882	$ 15,000	$ (258)	$ 0
Balance, end of the period, shares at Dec. 31, 2014	(19,571)	(19,571)					0