Mortgage Loans Credit Quality Indicators - SF (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	$ 3,064,669	[1]	$ 3,007,471	[1]
Government [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	48,600		50,900
Single-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	2,878,691	[1]	2,816,420	[1]
Single-Family [Member] | Primary [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	2,649,297	[1],[2],[3],[4]	2,544,315	[1],[2],[3],[4]
Single-Family [Member] | Primary [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Less Than or Equal to 80% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	2,073,079	[1],[2],[3],[4]	1,703,384	[1],[2],[3],[4]
Single-Family [Member] | Primary [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 80% and Less Than or Equal to 90% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	276,011	[1],[2],[3],[4]	346,018	[1],[2],[3],[4]
Single-Family [Member] | Primary [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 90% and Less Than or Equal to 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	153,474	[1],[2],[3],[4]	219,736	[1],[2],[3],[4]
Single-Family [Member] | Primary [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 100% and Less Than or Equal to 110% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	59,630	[1],[2],[3],[4]	100,302	[1],[2],[3],[4]
Single-Family [Member] | Primary [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 110% and Less Than or Equal to 120% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	33,954	[1],[2],[3],[4]	59,723	[1],[2],[3],[4]
Single-Family [Member] | Primary [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 120% and Less Than or Equal to 125% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	11,256	[1],[2],[3],[4]	20,620	[1],[2],[3],[4]
Single-Family [Member] | Primary [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 125% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	41,893	[1],[2],[3],[4]	94,532	[1],[2],[3],[4]
Single-Family [Member] | Alt-A [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	127,509	[1],[2],[3]	151,706	[1],[2],[3]
Single-Family [Member] | Alt-A [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Less Than or Equal to 80% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	61,670	[1],[2],[3]	57,419	[1],[2],[3]
Single-Family [Member] | Alt-A [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 80% and Less Than or Equal to 90% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	16,794	[1],[2],[3]	18,313	[1],[2],[3]
Single-Family [Member] | Alt-A [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 90% and Less Than or Equal to 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	14,709	[1],[2],[3]	16,930	[1],[2],[3]
Single-Family [Member] | Alt-A [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 100% and Less Than or Equal to 110% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	11,006	[1],[2],[3]	14,293	[1],[2],[3]
Single-Family [Member] | Alt-A [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 110% and Less Than or Equal to 120% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	7,742	[1],[2],[3]	10,994	[1],[2],[3]
Single-Family [Member] | Alt-A [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 120% and Less Than or Equal to 125% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	2,951	[1],[2],[3]	4,387	[1],[2],[3]
Single-Family [Member] | Alt-A [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 125% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	12,637	[1],[2],[3]	29,370	[1],[2],[3]
Single-Family [Member] | Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	53,291	[1],[2],[3],[5]	69,529	[1],[2],[3],[5]
Single-Family [Member] | Other [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Less Than or Equal to 80% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	24,112	[1],[2],[3],[5]	21,936	[1],[2],[3],[5]
Single-Family [Member] | Other [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 80% and Less Than or Equal to 90% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	6,947	[1],[2],[3],[5]	7,287	[1],[2],[3],[5]
Single-Family [Member] | Other [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 90% and Less Than or Equal to 100% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	6,402	[1],[2],[3],[5]	7,369	[1],[2],[3],[5]
Single-Family [Member] | Other [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 100% and Less Than or Equal to 110% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	5,146	[1],[2],[3],[5]	7,169	[1],[2],[3],[5]
Single-Family [Member] | Other [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 110% and Less Than or Equal to 120% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	3,691	[1],[2],[3],[5]	6,231	[1],[2],[3],[5]
Single-Family [Member] | Other [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 120% and Less Than or Equal to 125% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	1,406	[1],[2],[3],[5]	2,665	[1],[2],[3],[5]
Single-Family [Member] | Other [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 125% [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	5,587	[1],[2],[3],[5]	16,872	[1],[2],[3],[5]
Single-Family [Member] | Government [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment	$ 48,594	[1],[6]	$ 50,870	[1],[6]

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

[2] The aggregate estimated mark-to-market LTV ratio is based on the unpaid principal balance of the loan as of the end of each reported period divided by the estimated current value of the property, which we calculate using an internal valuation model that estimates periodic changes in home value.

[3] Excludes $48.6 billion and $50.9 billion as of December 31, 2013 and 2012, respectively, 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 loans. The segment class is primarily reverse mortgages for which we do not calculate an estimated mark-to-market LTV ratio.

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

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

[6] 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. Primarily consists of reverse mortgages which due to their nature are not aged and are included in the current column.