Investments in Securities Available-for-sale Securities 2 (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	$ 35,690	[1]	$ 61,766	[1]
Gross unrealized gains	3,364		3,464
Gross unrealized losses - OTTI	(385)	[2]	(1,369)	[2]
Gross unrealized losses, other	(498)	[3]	(680)	[3]
Total fair value	38,171		63,181
Fannie Mae [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	6,227	[1]	9,580	[1]
Gross unrealized gains	390		871
Gross unrealized losses - OTTI	0	[2]	0	[2]
Gross unrealized losses, other	(44)	[3]	(16)	[3]
Total fair value	6,573		10,435
Freddie Mac [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	6,365	[1]	8,652	[1]
Gross unrealized gains	477		728
Gross unrealized losses - OTTI	0	[2]	0	[2]
Gross unrealized losses, other	0	[3]	0	[3]
Total fair value	6,842		9,380
Ginnie Mae [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	512	[1]	645	[1]
Gross unrealized gains	76		106
Gross unrealized losses - OTTI	0	[2]	0	[2]
Gross unrealized losses, other	0	[3]	0	[3]
Total fair value	588		751
Alt-A private-label securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	6,240	[1]	11,356	[1]
Gross unrealized gains	1,151		452
Gross unrealized losses - OTTI	(40)	[2]	(637)	[2]
Gross unrealized losses, other	(2)	[3]	(96)	[3]
Total fair value	7,349		11,075
Subprime private-label securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	6,232	[1]	8,137	[1]
Gross unrealized gains	991		217
Gross unrealized losses - OTTI	(102)	[2]	(669)	[2]
Gross unrealized losses, other	(53)	[3]	(238)	[3]
Total fair value	7,068		7,447
CMBS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	1,526	[1]	12,284	[1]
Gross unrealized gains	80		824
Gross unrealized losses - OTTI	0	[2]	0	[2]
Gross unrealized losses, other	0	[3]	(11)	[3]
Total fair value	1,606		13,097
Mortgage revenue bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	5,645	[1]	7,782	[1]
Gross unrealized gains	35		157
Gross unrealized losses - OTTI	(228)	[2]	(45)	[2]
Gross unrealized losses, other	(196)	[3]	(52)	[3]
Total fair value	5,256		7,842
Other mortgage-related securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	2,943	[1]	3,330	[1]
Gross unrealized gains	164		109
Gross unrealized losses - OTTI	(15)	[2]	(18)	[2]
Gross unrealized losses, other	(203)	[3]	(267)	[3]
Total fair value	$ 2,889		$ 3,154

[1] Amortized cost consists of unpaid principal balance, unamortized premiums, discounts and other cost basis adjustments as well as net other-than-temporary impairments (“OTTI”) recognized in our consolidated statements of operations and comprehensive income (loss).

[2] Represents the noncredit component of other-than-temporary impairments losses recorded in “Accumulated other comprehensive income” as well as cumulative changes in fair value of securities for which we previously recognized the credit component of other-than-temporary impairments.

[3] Represents the gross unrealized losses on securities for which we have not recognized other-than-temporary impairments.