Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
ASSETS
Restricted cash (includes $20,550 and $23,982, respectively, related to consolidated trusts)	$ 24,583	$ 28,995
Investments in securities:
Available-for-sale, at fair value (includes $949 and $998, respectively, related to consolidated trusts)	37,128	38,171
Mortgage loans:
Loans held for sale, at lower of cost or fair value (includes $201 and $31, respectively, related to consolidated trusts)	1,494	380
Accrued interest receivable, net (includes $7,463 and $7,271, respectively, related to consolidated trusts)	8,459	8,319
Other assets (includes cash pledged as collateral of $1,291 and $1,590, respectively)	1,291	1,590
Liabilities:
Accrued interest payable (includes $8,262 and $8,276, respectively, related to consolidated trusts)	10,681	10,553
Other liabilities (includes $444 and $488, respectively, related to consolidated trusts)	13,012	15,441
Fannie Mae stockholders’ equity:
Senior preferred stock, 1,000,000 shares issued	1,000,000	1,000,000
Senior preferred stock, 1,000,000 shares outstanding	1,000,000	1,000,000
Preferred stock, 700,000,000 shares are authorized	700,000,000	700,000,000
Preferred stock, 555,374,922 shares issued	555,374,922	555,374,922
Common stock, no par value, no maximum authorization—1,308,762,703 shares issued	1,308,762,703	1,308,762,703
Common stock, no par value, no maximum authorization—1,158,080,657 shares outstanding	1,158,080,657	1,158,080,657
Treasury stock, at cost, 150,682,046 shares	150,682,046	150,682,046
Commitments and contingencies (Note 17)	0	0
Fannie Mae [Member]
Liabilities:
Debt at fair value	1,775	1,308
Consolidated Trusts [Member]
ASSETS
Restricted cash (includes $20,550 and $23,982, respectively, related to consolidated trusts)	20,550	23,982
Investments in securities:
Available-for-sale, at fair value (includes $949 and $998, respectively, related to consolidated trusts)	949	998
Mortgage loans:
Loans held for sale, at lower of cost or fair value (includes $201 and $31, respectively, related to consolidated trusts)	201	31
Loans held for investments, at amortized cost, of consolidated trusts (includes $14,637 and $14,268 respectively, at fair value)	14,637	14,268
Loans pledged as collateral that may be sold or repledged included in loans held for investment, at amortized cost	415	442
Accrued interest receivable, net (includes $7,463 and $7,271, respectively, related to consolidated trusts)	7,463	7,271
Liabilities:
Accrued interest payable (includes $8,262 and $8,276, respectively, related to consolidated trusts)	8,262	8,276
Debt at fair value	15,373	14,976
Other liabilities (includes $444 and $488, respectively, related to consolidated trusts)	$ 444	$ 488