Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Assets:
Cash and cash equivalents (includes $3 and $348, respectively, related to consolidated trusts)	$ 24,307	$ 17,297
Restricted cash (includes $51,774 and $59,619, respectively, related to consolidated trusts)	55,961	63,678
Federal funds sold and securities purchased under agreements to resell or similar arrangements	35,950	11,751
Investments in securities:
Trading, at fair value (includes $20 and $21, respectively, related to consolidated trusts)	68,149	56,856
Available-for-sale, at fair value (includes $1,429 and $1,055, respectively, related to consolidated trusts)	82,710	94,392
Total investments in securities	150,859	151,248
Mortgage loans:
Loans held for sale, at lower of cost or fair value (includes $53 and $661, respectively, related to consolidated trusts)	309	915
Loans held for investment, at amortized cost (includes $3,361 and $2,962, respectively, at fair value and loans pledged as collateral that may be sold or repledged of $6,993 and $2,522, respectively, related to consolidated trusts)	2,968,946	2,984,361
Allowance for loan losses	(71,435)	(61,556)
Total loans held for investment, net of allowance	2,897,511	2,922,805
Total mortgage loans	2,897,820	2,923,720
Accrued interest receivable, net (includes $8,451 and $8,910, respectively, related to consolidated trusts)	10,862	11,279
Acquired property, net	12,195	16,173
Other assets	25,923	26,826
Total assets	3,213,877	3,221,972
Liabilities:
Accrued interest payable (includes $9,449 and $9,712, respectively, related to consolidated trusts)	12,928	13,764
Federal funds purchased and securities sold under agreements to repurchase		52
Other liabilities (includes $674 and $893, respectively, related to consolidated trusts)	16,964	13,673
Total liabilities	3,221,668	3,224,489
Commitments and contingencies (Note 14)
Fannie Mae stockholders' equity (deficit):
Senior preferred stock, 1,000,000 shares issued and outstanding	104,787	88,600
Preferred stock, 700,000,000 shares are authorized - 555,374,922 and 576,868,139 shares issued and outstanding, respectively	19,130	20,204
Common stock, no par value, no maximum authorization - 1,308,762,703 and 1,270,092,708 shares issued, respectively; 1,157,757,042 and 1,118,504,194 shares outstanding, respectively	687	667
Accumulated deficit	(123,359)	(102,986)
Accumulated other comprehensive loss	(1,696)	(1,682)
Treasury stock, at cost, 151,005,661 and 151,588,514 shares, respectively	(7,402)	(7,402)
Total Fannie Mae stockholders' deficit	(7,853)	(2,599)
Noncontrolling interest	62	82
Total deficit	(7,791)	(2,517)
Total liabilities and deficit	3,213,877	3,221,972
Of Fannie Mae [Member]
Mortgage loans:
Loans held for investment, at amortized cost (includes $3,361 and $2,962, respectively, at fair value and loans pledged as collateral that may be sold or repledged of $6,993 and $2,522, respectively, related to consolidated trusts)	385,247	407,228
Liabilities:
Debt (includes $845 and $893, respectively, of debt of Fannie Mae and $3,840 and $2,271, respectively, of debt of consolidated trust, at fair value)	744,803	780,044
Of Consolidated Trusts [Member]
Assets:
Cash and cash equivalents (includes $3 and $348, respectively, related to consolidated trusts)	3	348
Restricted cash (includes $51,774 and $59,619, respectively, related to consolidated trusts)	51,774	59,619
Investments in securities:
Trading, at fair value (includes $20 and $21, respectively, related to consolidated trusts)	20	21
Available-for-sale, at fair value (includes $1,429 and $1,055, respectively, related to consolidated trusts)	1,429	1,055
Mortgage loans:
Loans held for sale, at lower of cost or fair value (includes $53 and $661, respectively, related to consolidated trusts)	53	661
Loans held for investment, at amortized cost (includes $3,361 and $2,962, respectively, at fair value and loans pledged as collateral that may be sold or repledged of $6,993 and $2,522, respectively, related to consolidated trusts)	2,583,699	2,577,133
Accrued interest receivable, net (includes $8,451 and $8,910, respectively, related to consolidated trusts)	8,451	8,910
Liabilities:
Accrued interest payable (includes $9,449 and $9,712, respectively, related to consolidated trusts)	9,449	9,712
Debt (includes $845 and $893, respectively, of debt of Fannie Mae and $3,840 and $2,271, respectively, of debt of consolidated trust, at fair value)	2,446,973	2,416,956
Other liabilities (includes $674 and $893, respectively, related to consolidated trusts)	$ 674	$ 893