Derivative Instruments Derivatives 1 - Notional and FV Position (Details) (USD $)	Dec. 31, 2013		Dec. 31, 2012
Asset Derivatives [Abstract]
Notional amount	$ 245,573,000,000		$ 396,866,000,000
Derivative asset, estimated fair value	2,073,000,000		435,000,000
Netting adjustment	(8,422,000,000)	[1]	(15,791,000,000)	[1]
Derivative Liabilities [Abstract]
Notional amount	380,094,000,000		464,145,000,000
Derivative liability, estimated fair value	(1,469,000,000)		(705,000,000)
Table Footnote [Abstract]
Cash collateral posted for derivative instruments	2,000,000,000		6,300,000,000
Cash collateral received for derivative instruments	1,000,000,000		0
Risk management derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	205,736,000,000		331,075,000,000
Derivative asset, estimated fair value	9,444,000,000		14,828,000,000
Accrued interest receivable, estimated fair value	786,000,000		1,242,000,000
Netting adjustment	(8,422,000,000)	[1],[2]	(15,791,000,000)	[1],[2]
Total net risk management derivatives	1,808,000,000		279,000,000
Derivative Liabilities [Abstract]
Notional amount	346,994,000,000		370,879,000,000
Derivative liability, estimated fair value	(9,695,000,000)		(20,946,000,000)
Accrued interest receivable (payable), estimated fair value	(930,000,000)		(1,508,000,000)
Netting adjustment	9,370,000,000	[1],[2]	22,046,000,000	[1],[2]
Total net risk management derivatives	(1,255,000,000)		(408,000,000)
Mortgage commitment derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	39,837,000,000		65,791,000,000
Derivative asset, estimated fair value	265,000,000		156,000,000
Netting adjustment	0	[1]	0	[1]
Derivative Liabilities [Abstract]
Notional amount	33,100,000,000		93,266,000,000
Derivative liability, estimated fair value	(214,000,000)		(297,000,000)
Netting adjustment	0	[1]	0	[1]
Pay-fixed Swap [Member] | Risk management derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	68,637,000,000		19,450,000,000
Derivative asset, estimated fair value	5,378,000,000		270,000,000
Derivative Liabilities [Abstract]
Notional amount	93,428,000,000		239,017,000,000
Derivative liability, estimated fair value	(4,759,000,000)		(18,237,000,000)
Receive-fixed Swap [Member] | Risk management derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	67,527,000,000		231,346,000,000
Derivative asset, estimated fair value	3,320,000,000		10,514,000,000
Derivative Liabilities [Abstract]
Notional amount	156,250,000,000		57,190,000,000
Derivative liability, estimated fair value	(3,813,000,000)		(200,000,000)
Basis Swap [Member] | Risk management derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	27,014,000,000		23,199,000,000
Derivative asset, estimated fair value	36,000,000		151,000,000
Derivative Liabilities [Abstract]
Notional amount	600,000,000		1,700,000,000
Derivative liability, estimated fair value	0		0
Foreign Currency Swap [Member] | Risk management derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	389,000,000		686,000,000
Derivative asset, estimated fair value	120,000,000		193,000,000
Derivative Liabilities [Abstract]
Notional amount	653,000,000		509,000,000
Derivative liability, estimated fair value	(38,000,000)		(45,000,000)
Pay-fixed Swaption [Member] | Risk management derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	33,400,000,000		33,050,000,000
Derivative asset, estimated fair value	445,000,000		102,000,000
Derivative Liabilities [Abstract]
Notional amount	48,025,000,000		36,225,000,000
Derivative liability, estimated fair value	(600,000,000)		(184,000,000)
Receive-fixed Swaption [Member] | Risk management derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	8,000,000,000		15,970,000,000
Derivative asset, estimated fair value	117,000,000		3,572,000,000
Derivative Liabilities [Abstract]
Notional amount	48,025,000,000		36,225,000,000
Derivative liability, estimated fair value	(484,000,000)		(2,279,000,000)
Other [Member] | Risk management derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	769,000,000	[3]	7,374,000,000	[3]
Derivative asset, estimated fair value	28,000,000	[3]	26,000,000	[3]
Derivative Liabilities [Abstract]
Notional amount	13,000,000	[3]	13,000,000	[3]
Derivative liability, estimated fair value	(1,000,000)	[3]	(1,000,000)	[3]
Mortgage Commitments to Purchase Whole Loans [Member] | Mortgage commitment derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	1,138,000,000		12,360,000,000
Derivative asset, estimated fair value	1,000,000		27,000,000
Derivative Liabilities [Abstract]
Notional amount	4,353,000,000		5,232,000,000
Derivative liability, estimated fair value	(31,000,000)		(8,000,000)
Forward Contracts to Purchase Mortgage-related Securities [Member] | Mortgage commitment derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	3,276,000,000		34,545,000,000
Derivative asset, estimated fair value	4,000,000		103,000,000
Derivative Liabilities [Abstract]
Notional amount	20,861,000,000		12,557,000,000
Derivative liability, estimated fair value	(168,000,000)		(23,000,000)
Forward Contracts to Sell Mortgage-related Securities [Member] | Mortgage commitment derivatives [Member]
Asset Derivatives [Abstract]
Notional amount	35,423,000,000		18,886,000,000
Derivative asset, estimated fair value	260,000,000		26,000,000
Derivative Liabilities [Abstract]
Notional amount	7,886,000,000		75,477,000,000
Derivative liability, estimated fair value	$ (15,000,000)		$ (266,000,000)

[1] Represents the effect of the right to offset under legally enforceable master netting agreements to settle with the same counterparty on a net basis, including cash collateral posted and received and accrued interest.

[2] The netting adjustment represents the effect of the legal right to offset under legally enforceable master netting agreements to settle with the same counterparty on a net basis, including cash collateral posted and received. Cash collateral posted was $2.0 billion and $6.3 billion as of December 31, 2013 and 2012, respectively. Since the agreements related to clearing contracts through derivatives clearing organizations do not provide us with a legal right of offset, no netting adjustments have been made for these contracts. Cash collateral received was $1.0 billion as of December 31, 2013. No cash collateral was received as of December 31, 2012.

[3] Includes interest rate caps, futures, swap credit enhancements and mortgage insurance contracts that we account for as derivatives. The mortgage insurance contracts have payment provisions that are not based on a notional amount.