Allowance for Loan Losses Allowance Rollforward (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Allowance for Loan Losses [Roll Forward]
Beginning balance	$ 58,795		$ 72,156		$ 61,556
(Benefit) provision for loan losses	(9,316)	[1]	(1,191)	[1]	25,914	[1]
Charge-offs	(8,867)	[2],[3]	(15,139)	[2],[3]	(21,170)	[2],[3]
Recoveries	2,626		1,784		5,272
Transfers	0	[4]	0	[4]	0	[4]
Other	608	[5]	1,185	[5]	584	[5]
Ending balance	43,846		58,795		72,156
Fannie Mae [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	50,519		57,309		48,530
(Benefit) provision for loan losses	(6,984)	[1]	(1,613)	[1]	14,080	[1]
Charge-offs	(8,611)	[2],[3]	(14,316)	[2],[3]	(19,398)	[2],[3]
Recoveries	2,115		1,632		3,636
Transfers	2,962	[4]	6,466	[4]	9,980	[4]
Other	520	[5]	1,041	[5]	481	[5]
Ending balance	40,521		50,519		57,309
Consolidated Trusts [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	8,276		14,847		13,026
(Benefit) provision for loan losses	(2,332)	[1]	422	[1]	11,834	[1]
Charge-offs	(256)	[2],[3]	(823)	[2],[3]	(1,772)	[2],[3]
Recoveries	511		152		1,636
Transfers	(2,962)	[4]	(6,466)	[4]	(9,980)	[4]
Other	88	[5]	144	[5]	103	[5]
Ending balance	3,325		8,276		14,847
Single-Family [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	57,687		70,633		59,980
(Benefit) provision for loan losses	(8,896)	[1]	(1,017)	[1]	25,623	[1]
Charge-offs	(8,714)	[3]	(14,878)	[3]	(20,798)	[3]
Recoveries	2,626		1,784		5,272
Transfers	0	[4]	0	[4]	0	[4]
Other	604	[5]	1,165	[5]	556	[5]
Ending balance	43,307		57,687		70,633
Single-Family [Member] | Fannie Mae [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	49,848		56,294		47,377
(Benefit) provision for loan losses	(6,751)	[1]	(1,482)	[1]	13,940	[1]
Charge-offs	(8,458)	[3]	(14,055)	[3]	(19,026)	[3]
Recoveries	2,115		1,632		3,636
Transfers	2,932	[4]	6,437	[4]	9,901	[4]
Other	516	[5]	1,022	[5]	466	[5]
Ending balance	40,202		49,848		56,294
Single-Family [Member] | Consolidated Trusts [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	7,839		14,339		12,603
(Benefit) provision for loan losses	(2,145)	[1]	465	[1]	11,683	[1]
Charge-offs	(256)	[3]	(823)	[3]	(1,772)	[3]
Recoveries	511		152		1,636
Transfers	(2,932)	[4]	(6,437)	[4]	(9,901)	[4]
Other	88	[5]	143	[5]	90	[5]
Ending balance	3,105		7,839		14,339
Multifamily [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	1,108		1,523		1,576
(Benefit) provision for loan losses	(420)	[1]	(174)	[1]	291	[1]
Charge-offs	(153)	[3]	(261)	[3]	(372)	[3]
Transfers	0	[4]	0	[4]	0	[4]
Other	4	[5]	20	[5]	28	[5]
Ending balance	539		1,108		1,523
Multifamily [Member] | Fannie Mae [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	671		1,015		1,153
(Benefit) provision for loan losses	(233)	[1]	(131)	[1]	140	[1]
Charge-offs	(153)	[3]	(261)	[3]	(372)	[3]
Transfers	30	[4]	29	[4]	79	[4]
Other	4	[5]	19	[5]	15	[5]
Ending balance	319		671		1,015
Multifamily [Member] | Consolidated Trusts [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance	437		508		423
(Benefit) provision for loan losses	(187)	[1]	(43)	[1]	151	[1]
Charge-offs	0	[3]	0	[3]	0	[3]
Transfers	(30)	[4]	(29)	[4]	(79)	[4]
Other	0	[5]	1	[5]	13	[5]
Ending balance	220		437		508
Interest Receivable [Member]
Allowance for Loan Losses [Roll Forward]
Charge-offs	(436)		(872)		(1,400)
Interest Receivable [Member] | Fannie Mae [Member]
Allowance for Loan Losses [Roll Forward]
Ending balance	1,100		1,500
Interest Receivable [Member] | Consolidated Trusts [Member]
Allowance for Loan Losses [Roll Forward]
Ending balance	$ 104		$ 192

[1] (Benefit) provision for loan losses is included in “Benefit (provision) for credit losses” in our consolidated statements of operations and comprehensive income (loss).

[2] Total charge-offs include accrued interest of $436 million, $872 million and $1.4 billion for the years ended December 31, 2013, 2012 and 2011, respectively.

[3] While we purchase the substantial majority of loans that are four or more months delinquent from our MBS trusts, we do not exercise this option to purchase loans during a forbearance period. Charge-offs of consolidated trusts generally represent loans that remained in our consolidated trusts at the time of default.

[4] Includes transfers from trusts for delinquent loan purchases.

[5] Amounts represent the net activity recorded in our allowances for accrued interest receivable and preforeclosure property taxes and insurance receivable from borrowers. The (benefit) provision for credit losses, charge-offs, recoveries and transfer activity included in this table reflects all changes for both the allowance for loan losses and the valuation allowances for accrued interest and preforeclosure property taxes and insurance receivable that relate to the mortgage loans.