Mortgage Loans Individually Impaired Loans (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	$ 184,871		$ 185,695
Individually impaired loans with related allowance recorded: total recorded investment	174,766	[1]	175,619	[1]
Related allowance for loan losses	36,838	[2]	37,729	[2]
Individually impaired loans with no related allowance recorded: unpaid principal balance	20,629	[3]	20,452	[3]
Individually impaired loans with no related allowance recorded: total recorded investment	18,127	[1],[3]	17,660	[1],[3]
Total individually impaired loans: unpaid principal balance	205,500	[2]	206,147	[2]
Total individually impaired loans: total recorded investment	192,893	[1],[2]	193,279	[1],[2]
Interest Receivable [Member]
Financing Receivable, Impaired [Line Items]
Related allowance for loan losses	636	[2]	688	[2]
Single-Family [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	182,989		183,438
Individually impaired loans with related allowance recorded: total recorded investment	172,869	[1]	173,343	[1]
Related allowance for loan losses	36,580		37,423
Individually impaired loans with no related allowance recorded: unpaid principal balance	18,923	[3]	18,525	[3]
Individually impaired loans with no related allowance recorded: total recorded investment	16,412	[1],[3]	15,721	[1],[3]
Table Footnote [Abstract]
Troubled debt restructuring recorded investment	187,900		187,600
Single-Family [Member] | Interest Receivable [Member]
Financing Receivable, Impaired [Line Items]
Related allowance for loan losses	629		678
Single-Family [Member] | Primary [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	130,023	[4]	130,080	[4]
Individually impaired loans with related allowance recorded: total recorded investment	123,571	[1],[4]	123,631	[1],[4]
Related allowance for loan losses	23,662	[4]	24,145	[4]
Individually impaired loans with no related allowance recorded: unpaid principal balance	14,392	[3],[4]	14,076	[3],[4]
Individually impaired loans with no related allowance recorded: total recorded investment	12,849	[1],[3],[4]	12,305	[1],[3],[4]
Single-Family [Member] | Primary [Member] | Interest Receivable [Member]
Financing Receivable, Impaired [Line Items]
Related allowance for loan losses	394	[4]	430	[4]
Single-Family [Member] | Government [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	272	[5]	213	[5]
Individually impaired loans with related allowance recorded: total recorded investment	276	[1],[5]	210	[1],[5]
Related allowance for loan losses	39	[5]	35	[5]
Individually impaired loans with no related allowance recorded: unpaid principal balance	66	[3],[5]	120	[3],[5]
Individually impaired loans with no related allowance recorded: total recorded investment	61	[1],[3],[5]	120	[1],[3],[5]
Single-Family [Member] | Government [Member] | Interest Receivable [Member]
Financing Receivable, Impaired [Line Items]
Related allowance for loan losses	12	[5]	5	[5]
Single-Family [Member] | Alt-A [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	37,108		37,356
Individually impaired loans with related allowance recorded: total recorded investment	34,219	[1]	34,479	[1]
Related allowance for loan losses	9,125		9,364
Individually impaired loans with no related allowance recorded: unpaid principal balance	3,396	[3]	3,290	[3]
Individually impaired loans with no related allowance recorded: total recorded investment	2,595	[1],[3]	2,428	[1],[3]
Single-Family [Member] | Alt-A [Member] | Interest Receivable [Member]
Financing Receivable, Impaired [Line Items]
Related allowance for loan losses	172		187
Single-Family [Member] | Other [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	15,586	[6]	15,789	[6]
Individually impaired loans with related allowance recorded: total recorded investment	14,803	[1],[6]	15,023	[1],[6]
Related allowance for loan losses	3,754	[6]	3,879	[6]
Individually impaired loans with no related allowance recorded: unpaid principal balance	1,069	[3],[6]	1,039	[3],[6]
Individually impaired loans with no related allowance recorded: total recorded investment	907	[1],[3],[6]	868	[1],[3],[6]
Single-Family [Member] | Other [Member] | Interest Receivable [Member]
Financing Receivable, Impaired [Line Items]
Related allowance for loan losses	51	[6]	56	[6]
Multifamily [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	1,882		2,257
Individually impaired loans with related allowance recorded: total recorded investment	1,897	[1]	2,276	[1]
Related allowance for loan losses	258		306
Individually impaired loans with no related allowance recorded: unpaid principal balance	1,706	[3]	1,927	[3]
Individually impaired loans with no related allowance recorded: total recorded investment	1,715	[1],[3]	1,939	[1],[3]
Table Footnote [Abstract]
Troubled debt restructuring recorded investment	897		911
Multifamily [Member] | Interest Receivable [Member]
Financing Receivable, Impaired [Line Items]
Related allowance for loan losses	$ 7		$ 10

[1] Recorded investment consists of unpaid principal balance, unamortized premiums, discounts and other cost basis adjustments, and accrued interest receivable.

[2] Includes single-family loans restructured in a TDR with a recorded investment of $187.9 billion and $187.6 billion as of March 31, 2014 and December 31, 2013, respectively. Includes multifamily loans restructured in a TDR with a recorded investment of $897 million and $911 million as of March 31, 2014 and December 31, 2013, respectively.

[3] The discounted cash flows or collateral value equals or exceeds the carrying value of the loan and, as such, no valuation allowance is required.

[4] Consists of mortgage loans that are not included in other loan classes.

[5] Consists of mortgage loans guaranteed or insured, in whole or in part, by the U.S. government or one of its agencies that are not Alt-A.

[6] Includes loans with higher-risk characteristics, such as interest-only loans and negative-amortizing loans, that are neither government nor Alt-A.