Fair Value Recurring Changes in Fair Value (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Trading securities	$ 27,064
Available-for-sale securities	0
Mortgage loans held for investment	0
Other assets [Abstract]
Derivatives assets at fair value	0
Total assets at fair value	95,727
Other liabilities [Abstract]
Derivatives	0
Total liabilities at fair value	0
Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Trading securities	21,566
Available-for-sale securities	43,366
Mortgage loans held for investment	2,441,818
Other assets [Abstract]
Derivatives assets at fair value	16,718
Total assets at fair value	2,566,436
Other liabilities [Abstract]
Derivatives	24,282
Total liabilities at fair value	3,337,177
Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Trading securities	2,305
Available-for-sale securities	26,328
Mortgage loans held for investment	523,752
Other assets [Abstract]
Derivatives assets at fair value	236
Total assets at fair value	554,289
Other liabilities [Abstract]
Derivatives	162
Total liabilities at fair value	24,551
Netting Adjustment [Member]
Assets [Abstract]
Trading securities	0
Available-for-sale securities	0
Mortgage loans held for investment	0
Other assets [Abstract]
Derivatives assets at fair value	(16,352)
Total assets at fair value	(16,352)
Other liabilities [Abstract]
Derivatives	(23,525)
Total liabilities at fair value	(23,525)
Estimated Fair Value [Member]
Assets [Abstract]
Trading securities	50,935		74,198
Available-for-sale securities	69,694		77,582
Mortgage loans held for investment	2,965,570		2,947,021
Other assets [Abstract]
Derivatives assets at fair value	602		561
Total assets at fair value	3,200,100		3,220,344
Other liabilities [Abstract]
Derivatives	919		916
Total liabilities at fair value	3,338,203		3,367,255
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Cash equivalents	7,699	[1]	600	[1]
Trading securities	27,064		47,737
Available-for-sale securities	0		0
Other assets [Abstract]
Derivatives assets at fair value	0		0
Total assets at fair value	34,763		48,337
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Other liabilities [Abstract]
Derivatives	0		0
Total liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Swap [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Swaption [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivatives	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
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]
Derivatives	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]
Derivatives	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	27,064		47,737
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Asset-Backed Securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Cash equivalents	0	[1]	0	[1]
Trading securities	21,566		22,223
Available-for-sale securities	43,366		48,090
Other assets [Abstract]
Derivatives assets at fair value	16,718		16,152
Total assets at fair value	84,550		87,757
Liabilities [Abstract]
Long-term debt, Fair Value	3,700		3,606
Other liabilities [Abstract]
Derivatives	24,282		22,641
Total liabilities at fair value	27,982		26,247
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Swap [Member]
Other assets [Abstract]
Derivatives assets at fair value	11,034		9,247
Other liabilities [Abstract]
Derivatives	20,968		18,661
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Swaption [Member]
Other assets [Abstract]
Derivatives assets at fair value	5,323		6,536
Other liabilities [Abstract]
Derivatives	2,686		3,432
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		1
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]
Derivatives	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	361		368
Other liabilities [Abstract]
Derivatives	628		548
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	6,737		5,687
Available-for-sale securities	13,154		15,904
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	2,972		2,732
Available-for-sale securities	10,972		12,811
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	282		278
Available-for-sale securities	829		902
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	1,108		1,004
Available-for-sale securities	4,727		4,427
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	9,930		10,411
Available-for-sale securities	13,668		14,026
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	4		7
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	12		13
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 Other Observable Inputs (Level 2) [Member] | Asset-Backed Securities [Member]
Assets [Abstract]
Trading securities	537		2,111
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Cash equivalents	0	[1]	0	[1]
Trading securities	2,305		4,238
Available-for-sale securities	26,328		29,492
Other assets [Abstract]
Derivatives assets at fair value	236		238
Total assets at fair value	31,200		36,287
Liabilities [Abstract]
Long-term debt, Fair Value	1,731		1,171
Other liabilities [Abstract]
Derivatives	162		173
Total liabilities at fair value	1,893		1,344
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Swap [Member]
Other assets [Abstract]
Derivatives assets at fair value	174		170
Other liabilities [Abstract]
Derivatives	159		167
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Swaption [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	55		51
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]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage Commitment Derivatives [Member]
Other assets [Abstract]
Derivatives assets at fair value	7		17
Other liabilities [Abstract]
Derivatives	3		6
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	82		1,737
Available-for-sale securities	34		946
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	2		0
Available-for-sale securities	11		12
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	0		9
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	188		345
Available-for-sale securities	6,456		7,256
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	1,226		1,280
Available-for-sale securities	7,230		7,586
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	689		724
Available-for-sale securities	9,353		10,247
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Assets [Abstract]
Trading securities	118		143
Available-for-sale securities	3,244		3,445
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] | Significant Unobservable Inputs (Level 3) [Member] | Asset-Backed Securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member]
Assets [Abstract]
Cash equivalents	0	[1]	0	[1]
Trading securities	0		0
Available-for-sale securities	0		0
Other assets [Abstract]
Derivatives assets at fair value	(16,352)	[2]	(15,829)	[2]
Total assets at fair value	(16,352)	[2]	(15,829)	[2]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Other liabilities [Abstract]
Derivatives	(23,525)	[2]	(21,898)	[2]
Total liabilities at fair value	(23,525)	[2]	(21,898)	[2]
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Swap [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Swaption [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives assets at fair value	(16,352)	[2]	(15,829)	[2]
Other liabilities [Abstract]
Derivatives	(23,525)	[2]	(21,898)	[2]
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]
Derivatives	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] | Netting Adjustment [Member] | Asset-Backed Securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Cash equivalents	7,699	[1]	600	[1]
Trading securities	50,935		74,198
Available-for-sale securities	69,694		77,582
Other assets [Abstract]
Derivatives assets at fair value	602		561
Total assets at fair value	134,161		156,552
Liabilities [Abstract]
Long-term debt, Fair Value	5,431		4,777
Other liabilities [Abstract]
Derivatives	919		916
Total liabilities at fair value	6,350		5,693
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Swap [Member]
Other assets [Abstract]
Derivatives assets at fair value	11,208		9,417
Other liabilities [Abstract]
Derivatives	21,127		18,828
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Swaption [Member]
Other assets [Abstract]
Derivatives assets at fair value	5,323		6,536
Other liabilities [Abstract]
Derivatives	2,686		3,432
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Other [Member]
Other assets [Abstract]
Derivatives assets at fair value	55		52
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives assets at fair value	(16,352)		(15,829)
Other liabilities [Abstract]
Derivatives	(23,525)		(21,898)
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Mortgage Commitment Derivatives [Member]
Other assets [Abstract]
Derivatives assets at fair value	368		385
Other liabilities [Abstract]
Derivatives	631		554
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	6,819		7,424
Available-for-sale securities	13,188		16,850
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	2,974		2,732
Available-for-sale securities	10,983		12,823
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	282		287
Available-for-sale securities	829		902
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	1,296		1,349
Available-for-sale securities	11,183		11,683
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	1,226		1,280
Available-for-sale securities	7,230		7,586
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	9,930		10,411
Available-for-sale securities	13,668		14,026
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	689		724
Available-for-sale securities	9,357		10,254
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Other [Member]
Assets [Abstract]
Trading securities	118		143
Available-for-sale securities	3,256		3,458
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | U.S. Treasury Securities [Member]
Assets [Abstract]
Trading securities	27,064		47,737
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Asset-Backed Securities [Member]
Assets [Abstract]
Trading securities	537		2,111
Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	831		838
Fannie Mae [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Mortgage loans held for investment	0
Liabilities [Abstract]
Long-term debt, Fair Value	0
Fannie Mae [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Mortgage loans held for investment	36,665
Liabilities [Abstract]
Long-term debt, Fair Value	592,491
Fannie Mae [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Mortgage loans held for investment	230,096
Liabilities [Abstract]
Long-term debt, Fair Value	1,074
Fannie Mae [Member] | Netting Adjustment [Member]
Assets [Abstract]
Mortgage loans held for investment	0
Liabilities [Abstract]
Long-term debt, Fair Value	0
Fannie Mae [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Mortgage loans held for investment	266,761		294,996
Liabilities [Abstract]
Long-term debt, Fair Value	593,565		613,983
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	419		432
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	419		432
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	412		406
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	412		406
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Netting Adjustment [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	831		838
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	419		432
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt, Fair Value	412		406
Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment	5,231		3,611
Liabilities [Abstract]
Long-term debt, Fair Value	4,600		3,939
Consolidated Trusts [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Mortgage loans held for investment	0
Liabilities [Abstract]
Long-term debt, Fair Value	0
Consolidated Trusts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Mortgage loans held for investment	2,405,153
Liabilities [Abstract]
Long-term debt, Fair Value	2,627,334
Consolidated Trusts [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Mortgage loans held for investment	293,656
Liabilities [Abstract]
Long-term debt, Fair Value	15,864
Consolidated Trusts [Member] | Netting Adjustment [Member]
Assets [Abstract]
Mortgage loans held for investment	0
Liabilities [Abstract]
Long-term debt, Fair Value	0
Consolidated Trusts [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Mortgage loans held for investment	2,698,809		2,652,025
Liabilities [Abstract]
Long-term debt, Fair Value	2,643,198		2,596,657
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Mortgage loans held for investment	0		0
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Mortgage loans held for investment	2,900		1,292
Liabilities [Abstract]
Long-term debt, Fair Value	3,281		3,174
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Mortgage loans held for investment	2,331		2,319
Liabilities [Abstract]
Long-term debt, Fair Value	1,319		765
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Netting Adjustment [Member]
Assets [Abstract]
Mortgage loans held for investment	0		0
Liabilities [Abstract]
Long-term debt, Fair Value	0		0
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Mortgage loans held for investment	5,231		3,611
Liabilities [Abstract]
Long-term debt, Fair Value	$ 4,600		$ 3,939

[1] Cash equivalents are comprised of U.S. Treasuries that are classified as Level 1.

[2] 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.