Fair Value Recurring Changes in Fair Value (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	$ 1,775		$ 1,308
Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	14,637		14,268
Liabilities [Abstract]
Long-term debt, fair value	15,373		14,976
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Trading securities	17,587		16,306
Available-for-sale securities	0		0
Mortgage loans held for investment, at fair value	0		0
Total assets at fair value	46,826		52,939
Other assets [Abstract]
Derivatives assets at fair value	0		0
Liabilities [Abstract]
Total liabilities at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	0		0
Liabilities [Abstract]
Long-term debt, fair value	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	0		0
Liabilities [Abstract]
Long-term debt, fair value	0		0
Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Trading securities	11,397		11,688
Available-for-sale securities	18,665		19,159
Mortgage loans held for investment, at fair value	2,616,855		2,599,667
Total assets at fair value	2,681,746		2,694,859
Other assets [Abstract]
Derivatives assets at fair value	9,160		10,430
Liabilities [Abstract]
Total liabilities at fair value	3,213,881		3,231,253
Other liabilities [Abstract]
Derivative liabilities at fair value	10,130		10,734
Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	28,725		29,920
Liabilities [Abstract]
Long-term debt, fair value	426,479		463,991
Significant Other Observable Inputs (Level 2) [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	2,588,130		2,569,747
Liabilities [Abstract]
Long-term debt, fair value	2,711,787		2,684,224
Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Trading securities	2,811		2,774
Available-for-sale securities	18,463		19,012
Mortgage loans held for investment, at fair value	394,999		392,355
Total assets at fair value	418,944		415,630
Other assets [Abstract]
Derivatives assets at fair value	98		65
Liabilities [Abstract]
Total liabilities at fair value	18,551		19,611
Other liabilities [Abstract]
Derivative liabilities at fair value	121		105
Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	213,181		215,960
Liabilities [Abstract]
Long-term debt, fair value	906		1,557
Significant Unobservable Inputs (Level 3) [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	181,818		176,395
Liabilities [Abstract]
Long-term debt, fair value	13,518		13,362
Netting Adjustment [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Mortgage loans held for investment, at fair value	0		0
Total assets at fair value	(8,422)		(8,422)
Other assets [Abstract]
Derivatives assets at fair value	(8,422)		(8,422)
Liabilities [Abstract]
Total liabilities at fair value	(10,042)		(9,370)
Other liabilities [Abstract]
Derivative liabilities at fair value	(10,042)		(9,370)
Netting Adjustment [Member] | Fannie Mae [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	0		0
Liabilities [Abstract]
Long-term debt, fair value	0		0
Netting Adjustment [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	0		0
Liabilities [Abstract]
Long-term debt, fair value	0		0
Estimated Fair Value [Member]
Assets [Abstract]
Trading securities	31,795		30,768
Available-for-sale securities	37,128		38,171
Mortgage loans held for investment, at fair value	3,011,854		2,992,022
Total assets at fair value	3,139,094		3,155,006
Other assets [Abstract]
Derivatives assets at fair value	836		2,073
Liabilities [Abstract]
Total liabilities at fair value	3,222,390		3,241,494
Other liabilities [Abstract]
Derivative liabilities at fair value	209		1,469
Estimated Fair Value [Member] | Fannie Mae [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	241,906		245,880
Liabilities [Abstract]
Long-term debt, fair value	427,385		465,548
Estimated Fair Value [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	2,769,948		2,746,142
Liabilities [Abstract]
Long-term debt, fair value	2,725,305		2,697,586
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Trading securities	17,587		16,306
Available-for-sale securities	0		0
Total assets at fair value	17,587		16,306
Other assets [Abstract]
Derivatives assets at fair value	0		0
Liabilities [Abstract]
Long-term debt, fair value	0		0
Total liabilities at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, fair value			0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	0		0
Liabilities [Abstract]
Long-term debt, fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	17,587		16,306
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Trading securities	11,397		11,688
Available-for-sale securities	18,665		19,159
Total assets at fair value	51,251		52,841
Other assets [Abstract]
Derivatives assets at fair value	9,160		10,430
Liabilities [Abstract]
Long-term debt, fair value	16,332		14,811
Total liabilities at fair value	26,462		25,545
Other liabilities [Abstract]
Derivative liabilities at fair value	10,130		10,734
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	8,643		9,604
Other liabilities [Abstract]
Derivative liabilities at fair value	8,970		9,444
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	413		561
Other liabilities [Abstract]
Derivative liabilities at fair value	1,047		1,084
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives assets at fair value	104		265
Other liabilities [Abstract]
Derivative liabilities at fair value	113		206
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	1,465		353
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, fair value			353
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	1,465		0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	12,029		11,564
Liabilities [Abstract]
Long-term debt, fair value	14,867		14,458
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	5,983		5,828
Available-for-sale securities	6,250		6,566
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	1,657		1,837
Available-for-sale securities	6,507		6,834
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	248		407
Available-for-sale securities	557		588
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	833		898
Available-for-sale securities	3,776		3,558
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	2,676		2,718
Available-for-sale securities	1,569		1,606
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	2		3
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	4		4
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Trading securities	2,811		2,774
Available-for-sale securities	18,463		19,012
Total assets at fair value	23,980		24,555
Other assets [Abstract]
Derivatives assets at fair value	98		65
Liabilities [Abstract]
Long-term debt, fair value	816		1,473
Total liabilities at fair value	937		1,578
Other liabilities [Abstract]
Derivative liabilities at fair value	121		105
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	68		36
Other liabilities [Abstract]
Derivative liabilities at fair value	115		96
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		1
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	29		28
Other liabilities [Abstract]
Derivative liabilities at fair value	1		1
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives assets at fair value	1		0
Other liabilities [Abstract]
Derivative liabilities at fair value	5		8
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	310		955
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, fair value			0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	310		955
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	2,608		2,704
Liabilities [Abstract]
Long-term debt, fair value	506		518
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	0		42
Available-for-sale securities	5		7
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	0		2
Available-for-sale securities	8		8
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	655		618
Available-for-sale securities	3,570		3,791
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	1,453		1,448
Available-for-sale securities	7,030		7,068
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	601		565
Available-for-sale securities	5,006		5,253
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Assets [Abstract]
Trading securities	102		99
Available-for-sale securities	2,844		2,885
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Total assets at fair value	(8,422)	[1]	(8,422)	[1]
Other assets [Abstract]
Derivatives assets at fair value	(8,422)	[1]	(8,422)	[1]
Liabilities [Abstract]
Long-term debt, fair value	0		0
Total liabilities at fair value	(10,042)	[1]	(9,370)	[1]
Other liabilities [Abstract]
Derivative liabilities at fair value	(10,042)	[1]	(9,370)	[1]
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivative liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives assets at fair value	(8,422)	[1]	(8,422)	[1]
Other liabilities [Abstract]
Derivative liabilities at fair value	(10,042)	[1]	(9,370)	[1]
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Fannie Mae [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, fair value			0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Fannie Mae [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	0		0
Liabilities [Abstract]
Long-term debt, fair value	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Other [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Trading securities	31,795		30,768
Available-for-sale securities	37,128		38,171
Total assets at fair value	84,396		85,280
Other assets [Abstract]
Derivatives assets at fair value	836		2,073
Liabilities [Abstract]
Long-term debt, fair value	17,148		16,284
Total liabilities at fair value	17,357		17,753
Other liabilities [Abstract]
Derivative liabilities at fair value	209		1,469
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives assets at fair value	8,711		9,640
Other liabilities [Abstract]
Derivative liabilities at fair value	9,085		9,540
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives assets at fair value	413		562
Other liabilities [Abstract]
Derivative liabilities at fair value	1,047		1,084
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	29		28
Other liabilities [Abstract]
Derivative liabilities at fair value	1		1
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives assets at fair value	105		265
Other liabilities [Abstract]
Derivative liabilities at fair value	118		214
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives assets at fair value	(8,422)		(8,422)
Other liabilities [Abstract]
Derivative liabilities at fair value	(10,042)		(9,370)
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, fair value	1,775		1,308
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Fannie Mae [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, fair value			353
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Fannie Mae [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, fair value	1,775		955
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment, at fair value	14,637		14,268
Liabilities [Abstract]
Long-term debt, fair value	15,373		14,976
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	5,983		5,870
Available-for-sale securities	6,255		6,573
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	1,657		1,839
Available-for-sale securities	6,515		6,842
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	248		407
Available-for-sale securities	557		588
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	1,488		1,516
Available-for-sale securities	7,346		7,349
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	1,453		1,448
Available-for-sale securities	7,030		7,068
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	2,676		2,718
Available-for-sale securities	1,569		1,606
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	601		565
Available-for-sale securities	5,008		5,256
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Other [Member]
Assets [Abstract]
Trading securities	102		99
Available-for-sale securities	2,848		2,889
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | U.S. Treasury securities [Member]
Assets [Abstract]
Trading securities	$ 17,587		$ 16,306

[1] Derivative contracts are reported on a gross basis by level. 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.