MBS (Details) (USD $)	6 Months Ended																				3 Months Ended		12 Months Ended
	Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2013 Agency MBS		Dec. 31, 2012 Agency MBS		Jun. 30, 2013 Agency MBS Fannie Mae.		Dec. 31, 2012 Agency MBS Fannie Mae.		Jun. 30, 2013 Agency MBS Freddie Mac.		Dec. 31, 2012 Agency MBS Freddie Mac.		Jun. 30, 2013 Agency MBS Ginnie Mae.		Dec. 31, 2012 Agency MBS Ginnie Mae.		Jun. 30, 2013 Non-Agency MBS		Dec. 31, 2012 Non-Agency MBS		Jun. 30, 2013 Non-Agency MBS Rated AAA		Dec. 31, 2012 Non-Agency MBS Rated AAA		Jun. 30, 2013 Non-Agency MBS Rated A		Dec. 31, 2012 Non-Agency MBS Rated A		Jun. 30, 2013 Non-Agency MBS Rated BBB		Dec. 31, 2012 Non-Agency MBS Rated BBB		Jun. 30, 2013 Non-Agency MBS Rated BB		Dec. 31, 2012 Non-Agency MBS Rated BB		Jun. 30, 2013 Non-Agency MBS Rated B		Dec. 31, 2012 Non-Agency MBS Rated B		Jun. 30, 2013 Non-Agency MBS Rated CCC		Dec. 31, 2012 Non-Agency MBS Rated CCC		Jun. 30, 2013 Non-Agency MBS Rated CC		Dec. 31, 2012 Non-Agency MBS Rated CC		Jun. 30, 2013 Non-Agency MBS Rated C		Dec. 31, 2012 Non-Agency MBS Rated C		Jun. 30, 2013 Non-Agency MBS Unrated and other		Dec. 31, 2012 Non-Agency MBS Unrated and other		Jun. 30, 2013 Non-Agency MBS D-rated Security	Dec. 31, 2012 Non-Agency MBS D-rated Security
Information about MBS
Minimum term of fixed rate mortgages underlying MBS	15 years
Principal/ Current Face	$ 12,956,750,000		$ 13,302,328,000		$ 6,667,993,000		$ 6,792,768,000		$ 5,388,034,000		$ 5,977,388,000		$ 1,266,355,000		$ 800,854,000		$ 13,604,000		$ 14,526,000		$ 6,288,757,000	[1]	$ 6,509,560,000	[1]	$ 19,831,000	[1]	$ 25,209,000	[1]	$ 961,000	[1]	$ 1,147,000	[1]	$ 48,809,000	[1]	$ 49,301,000	[1]	$ 107,733,000	[1]	$ 118,031,000	[1]	$ 281,447,000	[1]	$ 247,532,000	[1]	$ 1,161,319,000	[1]	$ 1,235,638,000	[1]	$ 420,330,000	[1]	$ 579,632,000	[1]	$ 463,562,000	[1]	$ 952,984,000	[1]	$ 3,784,765,000	[1],[2]	$ 3,300,086,000	[1],[2]
Purchase Premiums	233,252,000		228,256,000		232,503,000		227,384,000		184,066,000		196,686,000		48,203,000		30,447,000		234,000		251,000		749,000	[1]	872,000	[1]	107,000	[1]	158,000	[1]	20,000	[1]	24,000	[1]	563,000	[1]	637,000	[1]	47,000	[1]	39,000	[1]	0	[1]	0	[1]	12,000	[1]	14,000	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1],[2]	0	[1],[2]
Accretable Purchase Discounts	(396,664,000)		(371,684,000)		(83,000)		(58,000)		(83,000)		(58,000)		0		0		0		0		(396,581,000)	[1]	(371,626,000)	[1]	(191,000)	[1]	(219,000)	[1]	0	[1]	0	[1]	(1,266,000)	[1]	(1,741,000)	[1]	(8,395,000)	[1]	(8,892,000)	[1]	(30,377,000)	[1]	(31,133,000)	[1]	(111,764,000)	[1]	(107,618,000)	[1]	(28,895,000)	[1]	(41,191,000)	[1]	(45,691,000)	[1]	(55,294,000)	[1]	(170,002,000)	[1],[2]	(125,538,000)	[1],[2]
Discount Designated as Credit Reserve and OTTI	(1,264,971,000)	[3]	(1,380,506,000)	[3]	0	[3]	0	[3]	0	[3]	0	[3]	0	[3]	0	[3]	0	[3]	0	[3]	(1,264,971,000)	[1],[3]	(1,380,506,000)	[1],[3]	0	[1],[3]	0	[1],[3]	0	[1],[3]	0	[1],[3]	0	[1],[3]	(378,000)	[1],[3]	(884,000)	[1],[3]	(853,000)	[1],[3]	(12,437,000)	[1],[3]	(12,462,000)	[1],[3]	(178,567,000)	[1],[3]	(201,126,000)	[1],[3]	(96,002,000)	[1],[3]	(132,061,000)	[1],[3]	(72,795,000)	[1],[3]	(166,529,000)	[1],[3]	(904,286,000)	[1],[2],[3]	(867,097,000)	[1],[2],[3]
Amortized Cost	11,532,693,000	[4]	11,782,817,000	[4]	6,904,739,000	[4]	7,024,517,000	[4]	5,572,017,000	[4]	6,174,016,000	[4]	1,318,884,000	[4]	835,724,000	[4]	13,838,000	[4]	14,777,000	[4]	4,627,954,000	[1],[4]	4,758,300,000	[1],[4]	19,747,000	[1],[4]	25,148,000	[1],[4]	981,000	[1],[4]	1,171,000	[1],[4]	48,106,000	[1],[4]	47,819,000	[1],[4]	98,501,000	[1],[4]	108,325,000	[1],[4]	238,633,000	[1],[4]	203,937,000	[1],[4]	871,000,000	[1],[4]	926,908,000	[1],[4]	295,433,000	[1],[4]	406,380,000	[1],[4]	345,076,000	[1],[4]	731,161,000	[1],[4]	2,710,477,000	[1],[2],[4]	2,307,451,000	[1],[2],[4]	2,662,000,000	2,252,000,000
Fair Value	12,233,564,000		12,607,625,000		6,937,911,000		7,225,460,000		5,620,499,000		6,351,621,000		1,303,143,000		858,560,000		14,269,000		15,279,000		5,295,653,000	[1]	5,382,165,000	[1]	20,192,000	[1]	25,905,000	[1]	933,000	[1]	1,086,000	[1]	48,694,000	[1]	48,563,000	[1]	103,346,000	[1]	112,905,000	[1]	263,172,000	[1]	225,281,000	[1]	1,010,131,000	[1]	1,055,757,000	[1]	339,948,000	[1]	468,017,000	[1]	398,050,000	[1]	812,523,000	[1]	3,111,187,000	[1],[2]	2,632,128,000	[1],[2]	3,055,000,000	2,573,000,000
Gross Unrealized Gains	790,156,000		832,560,000		114,067,000		202,397,000		102,540,000		178,970,000		11,096,000		22,925,000		431,000		502,000		676,089,000	[1]	630,163,000	[1]	445,000	[1]	757,000	[1]	0	[1]	0	[1]	1,547,000	[1]	1,806,000	[1]	5,097,000	[1]	4,937,000	[1]	24,593,000	[1]	21,452,000	[1]	141,672,000	[1]	131,826,000	[1]	44,546,000	[1]	61,739,000	[1]	53,512,000	[1]	81,850,000	[1]	404,677,000	[1],[2]	325,796,000	[1],[2]
Gross Unrealized Losses	(89,285,000)		(7,752,000)		(80,895,000)		(1,454,000)		(54,058,000)		(1,365,000)		(26,837,000)		(89,000)		0		0		(8,390,000)	[1]	(6,298,000)	[1]	0	[1]	0	[1]	(48,000)	[1]	(85,000)	[1]	(959,000)	[1]	(1,062,000)	[1]	(252,000)	[1]	(357,000)	[1]	(54,000)	[1]	(108,000)	[1]	(2,541,000)	[1]	(2,977,000)	[1]	(31,000)	[1]	(102,000)	[1]	(538,000)	[1]	(488,000)	[1]	(3,967,000)	[1],[2]	(1,119,000)	[1],[2]
Net Unrealized Gain/(Loss)	700,871,000		824,808,000		33,172,000		200,943,000		48,482,000		177,605,000		(15,741,000)		22,836,000		431,000		502,000		667,699,000	[1]	623,865,000	[1]	445,000	[1]	757,000	[1]	(48,000)	[1]	(85,000)	[1]	588,000	[1]	744,000	[1]	4,845,000	[1]	4,580,000	[1]	24,539,000	[1]	21,344,000	[1]	139,131,000	[1]	128,849,000	[1]	44,515,000	[1]	61,637,000	[1]	52,974,000	[1]	81,362,000	[1]	400,710,000	[1],[2]	324,677,000	[1],[2]
Credit Reserve																					1,219,000,000		1,332,000,000
OTTI																					45,700,000		48,700,000
Principal payments receivable	$ 4,300,000		$ 4,400,000
Number of mortgage backed securities held																																																													312	246

[1] Non-Agency MBS, including Non-Agency MBS transferred to consolidated VIEs, are reported based on the lowest rating issued by a Rating Agency, if more than one rating is issued on the security, at the date presented.

[2] Includes 312 Non-Agency MBS that were D-rated and had an aggregate amortized cost and fair value of $2.662 billion and $3.055 billion, respectively, at June 30, 2013 and 246 Non-Agency MBS that were D-rated and had an aggregate amortized cost and fair value of $2.252 billion and $2.573 billion, respectively, at December 31, 2012.

[3] Discount designated as Credit Reserve and amounts related to OTTI are generally not expected to be accreted into interest income. Amounts disclosed at June 30, 2013 reflect Credit Reserve of $1.219 billion and OTTI of $45.7 million. Amounts disclosed at December 31, 2012 reflect Credit Reserve of $1.332 billion and OTTI of $48.7 million.

[4] Includes principal payments receivable of $4.3 million and $4.4 million at June 30, 2013 and December 31, 2012, respectively, which are not included in the Principal/Current Face.