Summary of Significant Accounting Policies Narratives(Details) (USD $)	0 Months Ended	3 Months Ended		9 Months Ended			0 Months Ended	3 Months Ended				9 Months Ended								3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended				9 Months Ended					3 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2014 Scenario, Forecast [Member]	Sep. 30, 2014 US Treasury [Member]		Sep. 30, 2013 US Treasury [Member]		Sep. 30, 2014 US Treasury [Member]		Sep. 30, 2013 US Treasury [Member]		Sep. 30, 2014 US Treasury [Member] Temporary Credit and Liquidity Facilities Program [Member]	Dec. 31, 2013 US Treasury [Member] Temporary Credit and Liquidity Facilities Program [Member]	Sep. 30, 2014 US Treasury [Member] New Issue Bond [Member]	Dec. 31, 2013 US Treasury [Member] New Issue Bond [Member]	Sep. 30, 2014 Freddie Mac [Member]	Sep. 30, 2013 Freddie Mac [Member]	Sep. 30, 2014 Freddie Mac [Member]	Sep. 30, 2013 Freddie Mac [Member]	Dec. 31, 2013 Freddie Mac [Member]	Sep. 30, 2014 Federal Housing Finance Agency [Member]	Sep. 30, 2013 Federal Housing Finance Agency [Member]	Sep. 30, 2014 Federal Housing Finance Agency [Member]	Sep. 30, 2013 Federal Housing Finance Agency [Member]	Sep. 30, 2014 Single-Family [Member] US Treasury [Member]		Sep. 30, 2013 Single-Family [Member] US Treasury [Member]		Sep. 30, 2014 Single-Family [Member] US Treasury [Member]		Sep. 30, 2013 Single-Family [Member] US Treasury [Member]		Sep. 30, 2014 Mortgage Backed Private Label Securities and Repurchase Request Resolution Agreement [Member]	Sep. 30, 2014 Single-Family Individually Impaired Loan Loss Models Update [Member]
Related Parties [Line Items]
Number of days after which we have not been paying debts or liabilities exceed assets FHFA must place us into receivership				60 days
Aggregate funding received from US Treasury pursuant to the senior preferred stock purchase agreement								$ 116,100,000,000				$ 116,100,000,000
Initial aggregate liquidation preference of senior preferred stock held by US Treasury								1,000,000,000				1,000,000,000
Aggregate liquidation preference of senior preferred stock								117,100,000,000				117,100,000,000
Total available funding from US Treasury pursuant to the senior preferred stock agreement								117,600,000,000				117,600,000,000
Payments of cash dividends on senior preferred stock to Treasury	3,700,000,000			16,594,000,000	73,835,000,000
Expected undeclared dividends payable on senior preferred stock for the next quarter							4,000,000,000
Deficit of core capital over statutory minimum capital requirement		139,700,000,000		139,700,000,000		137,300,000,000
Percentage of common shares attributable to warrants issued to US Treasury as percentage to total diluted common shares								79.90%				79.90%
Home Affordable Modification Program administrative expense reimbursements from Treasury and Freddie Mac		18,000,000	23,000,000	55,000,000	73,000,000
Income Taxes Paid				2,475,000,000	1,876,000,000					860,000,000		2,500,000,000		1,900,000,000
Principal and interest outstanding																450,000,000	821,000,000	4,300,000,000	4,500,000,000
Percentage of initial principal loss US Treasury will bear for Temporary Credit and Liquidity Facilities and New Issue Bond Programs								35.00%				35.00%
Loss of principal or interest under Treasury's Temporary Credit and Liquidity Facility and New Issue Bond Programs								0				0
Temporary Payroll Tax Cut Continuation Act of 2011 (“TCCA”) fees		351,000,000	276,000,000	1,008,000,000	695,000,000			351,000,000	[1]	276,000,000	[1],[2]	1,008,000,000	[1]	695,000,000	[1],[2]														351,000,000	[1]	276,000,000	[1],[2]	1,008,000,000	[1]	695,000,000	[1],[2]
Liability to Treasury Related to Increase in Single-Family Guaranty Fee Resulting from the Temporary Payroll Tax Cut Continuation Act of 2011																													351,000,000				351,000,000
Temporary Payroll Tax Cut related guaranty fee paid to US Treasury																													335,000,000
Fair value of mortgage-backed securities																				7,300,000,000		7,300,000,000		8,700,000,000
Investment income, interest																				68,000,000	91,000,000	219,000,000	303,000,000
FHFA assessment fees																									26,000,000	28,000,000	80,000,000	83,000,000
Allowance for Loan and Lease Losses, Period Increase (Decrease)																																						600,000,000
Fee and other income		$ 826,000,000	$ 741,000,000	$ 5,564,000,000	$ 1,794,000,000																																$ 4,800,000,000

[1] Includes the impact of a 10 basis point guaranty fee increase implemented pursuant to the TCCA, the incremental revenue from which must be remitted to Treasury. The resulting revenue is included in guaranty fee income and the expense is recognized as “TCCA fees.”

[2] Certain prior period amounts have been reclassified to conform to our current period presentation.