Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
ASSETS
Restricted cash	$ 53,930	$ 67,919
Investments in securities:
Available-for-sale, at fair value	55,536	63,181
Mortgage loans:
Loans held for sale, at lower of cost or fair value	545	464
Accrued interest receivable, net	8,997	9,176
Cash pledged as collateral included in other assets	981	1,222
Liabilities:
Accrued interest payable	10,613	11,303
Other liabilities	16,274	14,378
Fannie Mae stockholders' equity (deficit):
Senior preferred stock issued	1,000,000	1,000,000
Senior preferred stock outstanding	1,000,000	1,000,000
Preferred stock authorized	700,000,000	700,000,000
Preferred stock issued	555,374,922	555,374,922
Preferred stock outstanding	555,374,922	555,374,922
Common stock issued	1,308,762,703	1,308,762,703
Common stock outstanding	1,158,077,970	1,158,077,970
Treasury stock, shares	150,684,733	150,684,733
Fannie Mae [Member]
Liabilities:
Debt at fair value	720	793
Consolidated Trusts [Member]
ASSETS
Restricted cash	48,774	61,976
Investments in securities:
Available-for-sale, at fair value	665	935
Mortgage loans:
Loans held for sale, at lower of cost or fair value	101	72
Mortgage loans held for investment, at amortized cost	13,770	10,800
Loans pledged as collateral that may be sold or repledged included in loans held for investment, at amortized cost	524	943
Accrued interest receivable, net	7,725	7,567
Liabilities:
Accrued interest payable	8,275	8,645
Debt at fair value	14,601	11,647
Other liabilities	$ 366	$ 1,059