Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Assets:
Cash and cash equivalents	$ 23,860	$ 22,023
Restricted cash (includes $36,921 and $27,515, respectively, related to consolidated trusts)	41,439	32,542
Federal funds sold and securities purchased under agreements to resell or similar arrangements	20,230	30,950
Investments in securities:
Trading, at fair value	31,286	31,504
Available-for-sale, at fair value (includes $468 and $596, respectively, related to consolidated trusts)	27,732	30,654
Total investments in securities	59,018	62,158
Mortgage loans:
Loans held for sale, at lower of cost or fair value	613	331
Loans held for investment, at amortized cost	3,044,323	3,054,704
Allowance for loan losses	(31,820)	(35,541)
Total loans held for investment, net of allowance	3,012,503	3,019,163
Total mortgage loans	3,013,116	3,019,494
Accrued interest receivable, net (includes $7,259 and $7,169, respectively, related to consolidated trusts)	7,990	8,193
Acquired property, net	9,518	10,618
Deferred tax assets, net	41,983	42,206
Other assets	20,959	19,992
Total assets	3,238,113	3,248,176
Liabilities:
Accrued interest payable (includes $8,223 and $8,282, respectively, related to consolidated trusts)	10,324	10,232
Federal funds purchased and securities sold under agreements to repurchase	87	50
Other liabilities (includes $437 and $503, respectively, related to consolidated trusts)	11,475	12,019
Total liabilities	3,234,517	3,244,456
Commitments and contingencies (Note 16)	0	0
Fannie Mae stockholders’ equity:
Senior preferred stock, 1,000,000 shares issued and outstanding	117,149	117,149
Preferred stock, 700,000,000 shares are authorized—555,374,922 shares issued and outstanding	19,130	19,130
Common stock, no par value, no maximum authorization—1,308,762,703 shares issued and 1,158,082,750 shares outstanding	687	687
Accumulated deficit	(127,651)	(127,618)
Accumulated other comprehensive income	1,641	1,733
Treasury stock, at cost, 150,679,953 shares	(7,401)	(7,401)
Total Fannie Mae stockholders’ equity	3,555	3,680
Noncontrolling interest	41	40
Total equity (See Note 1: Impact of U.S. Government Support for information on our dividend obligation to Treasury)	3,596	3,720
Total liabilities and equity	3,238,113	3,248,176
Fannie Mae [Member]
Mortgage loans:
Loans held for investment, at amortized cost	265,700	272,360
Allowance for loan losses	(29,873)	(33,117)
Total mortgage loans	236,416	239,549
Liabilities:
Debt (includes $7,920 and $6,403, respectively, of debt of Fannie Mae at fair value and $21,373 and $19,483, respectively, of debt of consolidated trusts, at fair value)	448,740	460,443
Consolidated Trusts [Member]
Assets:
Restricted cash (includes $36,921 and $27,515, respectively, related to consolidated trusts)	36,921	27,515
Investments in securities:
Available-for-sale, at fair value (includes $468 and $596, respectively, related to consolidated trusts)	468	596
Mortgage loans:
Loans held for investment, at amortized cost	2,778,623	2,782,344
Allowance for loan losses	(1,947)	(2,424)
Total mortgage loans	2,776,700	2,779,945
Accrued interest receivable, net (includes $7,259 and $7,169, respectively, related to consolidated trusts)	7,259	7,169
Liabilities:
Accrued interest payable (includes $8,223 and $8,282, respectively, related to consolidated trusts)	8,223	8,282
Debt (includes $7,920 and $6,403, respectively, of debt of Fannie Mae at fair value and $21,373 and $19,483, respectively, of debt of consolidated trusts, at fair value)	2,763,891	2,761,712
Other liabilities (includes $437 and $503, respectively, related to consolidated trusts)	$ 437	$ 503