Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows provided by (used in) operating activities:
Net income (loss)	$ 17,220	$ (16,855)	$ (14,018)
Reconciliation of net income (loss) to net cash provided by (used in) operating activities:
Amortization of cost basis adjustments	(2,335)	(369)	126
(Benefit) provision for credit losses	(852)	26,718	24,896
Valuation (gains) losses	(1,345)	(408)	(1,289)
(Gains) losses from partnership investments	(119)	(82)	74
Current and deferred federal income taxes	10	1,044	258
Purchases of loans held for sale	(603)	(737)	(81)
Proceeds from repayments and sales of loans held for sale	177	68	88
Net change in trading securities, excluding non-cash transfers	31,972	(17,048)	(23,612)
Payments for foreclosed property expenses	(5,722)	(5,394)	(5,658)
Other, net	(1,402)	(2,175)	(8,179)
Net cash provided by (used in) operating activities	37,001	(15,238)	(27,395)
Cash flows provided by investing activities:
Purchases of trading securities held for investment	(3,216)	(2,951)	(8,547)
Proceeds from maturities and paydowns of trading securities held for investment	3,508	2,591	2,638
Proceeds from sales of trading securities held for investment	3,861	1,526	21,556
Purchases of available-for-sale securities	(34)	(192)	(413)
Proceeds from maturities and paydowns of available-for-sale securities	12,636	13,552	17,102
Proceeds from sales of available-for-sale securities	1,306	3,192	7,867
Purchases of loans held for investment	(210,488)	(78,099)	(86,724)
Net change in restricted cash	(17,122)	12,881	(15,025)
Advances to lenders	(144,064)	(70,914)	(74,130)
Proceeds from disposition of acquired property and preforeclosure sales	38,685	47,248	39,682
Net change in federal funds sold and securities purchased under agreements to resell or similar agreements	13,500	(34,249)	41,471
Other, net	468	468	(753)
Net cash provided by investing activities	527,693	464,388	540,179
Cash flows used in financing activities:
Payments of cash dividends on senior preferred stock to Treasury	(11,608)	(9,613)	(7,706)
Proceeds from senior preferred stock purchase agreement with Treasury	4,571	23,978	27,700
Other, net	(9)	146	4
Net cash used in financing activities	(561,116)	(448,908)	(502,299)
Net increase (decrease) in cash and cash equivalents	3,578	242	10,485
Cash and cash equivalents at beginning of period	17,539	17,297	6,812
Cash and cash equivalents at end of period	21,117	17,539	17,297
Cash paid during the period for:
Interest	119,259	128,806	140,651
Non-cash activities:
Net mortgage loans acquired by assuming debt	537,862	448,437	484,699
Net transfers from (to) mortgage loans of Fannie Mae to (from) mortgage loans of consolidated trusts	165,272	33,859	(121,852)
Transfers from advances to lenders to loans held for investment of consolidated trusts	133,554	69,223	68,385
Net transfers from mortgage loans to acquired property	46,981	56,517	66,081
Fannie Mae [Member]
Cash flows provided by investing activities:
Proceeds from repayments of loans held for investment	31,322	25,190	20,715
Cash flows used in financing activities:
Proceeds from the issuance of debt	736,065	766,598	1,155,993
Payments to redeem debt	(854,111)	(815,838)	(1,146,363)
Consolidated Trusts [Member]
Cash flows provided by investing activities:
Proceeds from repayments of loans held for investment	797,331	544,145	574,740
Cash flows used in financing activities:
Proceeds from the issuance of debt	396,513	233,516	276,575
Payments to redeem debt	$ (832,537)	$ (647,695)	$ (808,502)