Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $) In Millions, except Share data	Jun. 30, 2011	Dec. 31, 2010
Assets:
Cash and cash equivalents	$ 14,274	$ 17,297
Restricted cash	37,579	63,678
Investments in securities:
Trading, at fair value	61,907	56,856
Available-for-sale, at fair value	86,616	94,392
Mortgage loans:
Loans held for sale, at lower of cost or fair value	439	915
Accrued interest receivable, net	10,681	11,279
Other assets	24,134	26,826
Liabilities:
Accrued interest payable	13,289	13,764
Other liabilities	13,065	13,673
Fannie Mae stockholders' equity (deficit):
Senior preferred stock issued (in shares)	1,000,000	1,000,000
Senior preferred stock outstanding (in shares)	1,000,000	1,000,000
Preferred stock authorized (in shares)	700,000,000	700,000,000
Preferred stock issued (in shares)	555,374,922	576,868,139
Preferred stock outstanding (in shares)	555,374,922	576,868,139
Common stock par or stated value per share (in shares)
Common stock authorized (in shares)	no maximum	no maximum
Common stock issued (in shares)	1,308,762,703	1,270,092,708
Common stock outstanding (in shares)	1,157,750,434	1,118,504,194
Treasury stock ( in shares)	151,012,269	151,588,514
Of Fannie Mae [Member]
Liabilities:
Debt at fair value included in debt	862	893
Of Consolidated Trusts [Member]
Assets:
Cash and cash equivalents	3	348
Restricted cash	33,136	59,619
Investments in securities:
Trading, at fair value	21	21
Available-for-sale, at fair value	1,590	1,055
Mortgage loans:
Loans held for sale, at lower of cost or fair value	73	661
Loans at fair value included in loans held for investment, at amortized cost	3,084	2,962
Loans pledged as collateral that may be sold or repledged included in loans held for investment, at amortized cost	460	2,522
Accrued interest receivable, net	8,683	8,910
Other assets	59	593
Liabilities:
Accrued interest payable	9,584	9,712
Debt at fair value included in debt	3,273	2,271
Other liabilities	$ 707	$ 893