Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
ASSETS
Restricted cash	$ 31,525	$ 67,919
Investments in securities:
Available-for-sale, at fair value	41,000	63,181
Mortgage loans:
Loans held for sale, at lower of cost or fair value	998	464
Accrued interest receivable, net	8,696	9,176
Cash pledged as collateral included in other assets	2,635	1,222
Liabilities:
Accrued interest payable	10,769	11,303
Other liabilities	18,715	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	1,158,080,657	1,158,077,970
Treasury stock, shares	150,682,046	150,684,733
Fannie Mae [Member]
Liabilities:
Debt at fair value	684	793
Consolidated Trusts [Member]
ASSETS
Restricted cash	26,804	61,976
Investments in securities:
Available-for-sale, at fair value	911	935
Mortgage loans:
Loans held for sale, at lower of cost or fair value	41	72
Mortgage loans held for investment, at fair value	13,877	10,800
Loans pledged as collateral that may be sold or repledged included in loans held for investment, at amortized cost	477	943
Accrued interest receivable, net	7,568	7,567
Liabilities:
Accrued interest payable	8,234	8,645
Debt at fair value	14,414	11,647
Other liabilities	$ 501	$ 1,059