Consolidated Statements Of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Preferred Stock [Member]	Common Stock [Member]	Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2008	$ 179,460	$ 631	$ 975,893	$ (358,155)	$ (37,379)	$ 760,450
Net income				129,263		129,263
Change in unrealized gain on mortgage securities, net					169,145	169,145
Amounts related to cash flow hedges, net					41,118	41,118
Cash dividends:
Common			(39,093)	(109,487)		(148,580)
Preferred			(2,464)	(17,775)		(20,239)
Conversion of preferred stock	(127)		127
Additions to capital		62	82,722			82,784
Balance at Dec. 31, 2009	179,333	693	1,017,185	(356,154)	172,884	1,013,941
Net income				126,896		126,896
Change in unrealized gain on mortgage securities, net					1,057	1,057
Amounts related to cash flow hedges, net					(41)	(41)
Cash dividends:
Common			(546)	(105,392)		(105,938)
Preferred				(20,233)		(20,233)
Conversion of preferred stock	(10)		10
Additions to capital		10	11,733			11,743
Balance at Dec. 31, 2010	179,323	703	1,028,382	(354,883)	173,900	1,027,425
Net income				160,204		160,204
Change in unrealized gain on mortgage securities, net					54,325	54,325
Amounts related to cash flow hedges, net					(23,685)	(23,685)
Cash dividends:
Common			(5,407)	(139,835)		(145,242)
Preferred				(20,369)		(20,369)
Conversion of preferred stock	(15)		15
Additions to capital	5,206	180	234,663			240,049
Balance at Dec. 31, 2011	$ 184,514	$ 883	$ 1,257,653	$ (354,883)	$ 204,540	$ 1,292,707