Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Cash and cash equivalents	$ 22,023,000,000	$ 19,228,000,000
Restricted cash (includes $27,515 and $23,982, respectively, related to consolidated trusts)	32,542,000,000	28,995,000,000
Federal funds sold and securities purchased under agreements to resell or similar arrangements	30,950,000,000	38,975,000,000
Investments in securities:
Trading, at fair value	31,504,000,000	30,768,000,000
Available-for-sale, at fair value (includes $596 and $998, respectively, related to consolidated trusts)	30,654,000,000	38,171,000,000
Total investments in securities	62,158,000,000	68,939,000,000
Mortgage loans:
Loans held for sale, at lower of cost or fair value	331,000,000	380,000,000
Loans held for investment, at amortized cost	3,054,704,000,000	3,069,706,000,000
Allowance for loan losses	(35,541,000,000)	(43,846,000,000)
Total loans held for investment, net of allowance	3,019,163,000,000	3,025,860,000,000
Total mortgage loans	3,019,494,000,000	3,026,240,000,000
Accrued interest receivable, net (includes $7,169 and $7,271, respectively, related to consolidated trusts)	8,193,000,000	8,319,000,000
Acquired property, net	10,618,000,000	11,621,000,000
Deferred tax assets, net	42,206,000,000	47,560,000,000
Other assets (includes cash pledged as collateral of $1,646 and $1,590, respectively)	19,992,000,000	20,231,000,000
Total assets	3,248,176,000,000	3,270,108,000,000
Liabilities:
Accrued interest payable (includes $8,282 and $8,276, respectively, related to consolidated trusts)	10,232,000,000	10,553,000,000
Federal funds purchased and securities sold under agreements to repurchase	50,000,000	0
Other liabilities (includes $503 and $488, respectively, related to consolidated trusts)	12,019,000,000	15,441,000,000
Total liabilities	3,244,456,000,000	3,260,517,000,000
Commitments and contingencies (Note 19)	0	0
Fannie Mae stockholders’ equity:
Senior preferred stock, 1,000,000 shares issued and outstanding	117,149,000,000	117,149,000,000
Preferred stock, 700,000,000 shares are authorized— 555,374,922 shares issued and outstanding	19,130,000,000	19,130,000,000
Common stock, no par value, no maximum authorization—1,308,762,703 shares issued, 1,158,082,750 and 1,158,080,657 shares outstanding, respectively	687,000,000	687,000,000
Accumulated deficit	(127,618,000,000)	(121,227,000,000)
Accumulated other comprehensive income	1,733,000,000	1,203,000,000
Treasury stock, at cost, 150,679,953 and 150,682,046 shares, respectively	(7,401,000,000)	(7,401,000,000)
Total Fannie Mae stockholders’ equity	3,680,000,000	9,541,000,000
Noncontrolling interest	40,000,000	50,000,000
Total equity (See Note 1: Senior Preferred Stock and Warrant Issued to Treasury and (Loss) Earnings per Share for information on our dividend obligation to Treasury)	3,720,000,000	9,591,000,000
Total liabilities and equity	3,248,176,000,000	3,270,108,000,000
Fannie Mae [Member]
Mortgage loans:
Loans held for investment, at amortized cost	272,360,000,000	300,159,000,000
Allowance for loan losses	(33,117,000,000)	(40,521,000,000)
Total mortgage loans	239,549,000,000	259,987,000,000
Liabilities:
Debt (includes $6,403 and $1,308, respectively, of debt of Fannie Mae and $19,483 and $14,976, respectively, of debt of consolidated trusts, at fair value)	460,443,000,000	529,434,000,000
Consolidated Trusts [Member]
ASSETS
Restricted cash (includes $27,515 and $23,982, respectively, related to consolidated trusts)	27,515,000,000	23,982,000,000
Investments in securities:
Available-for-sale, at fair value (includes $596 and $998, respectively, related to consolidated trusts)	596,000,000	998,000,000
Mortgage loans:
Loans held for investment, at amortized cost	2,782,344,000,000	2,769,547,000,000
Allowance for loan losses	(2,424,000,000)	(3,325,000,000)
Total mortgage loans	2,779,945,000,000	2,766,253,000,000
Accrued interest receivable, net (includes $7,169 and $7,271, respectively, related to consolidated trusts)	7,169,000,000	7,271,000,000
Liabilities:
Accrued interest payable (includes $8,282 and $8,276, respectively, related to consolidated trusts)	8,282,000,000	8,276,000,000
Debt (includes $6,403 and $1,308, respectively, of debt of Fannie Mae and $19,483 and $14,976, respectively, of debt of consolidated trusts, at fair value)	2,761,712,000,000	2,705,089,000,000
Other liabilities (includes $503 and $488, respectively, related to consolidated trusts)	$ 503,000,000	$ 488,000,000