Summary of Significant Accounting Policies Narratives (Details) (USD $)	0 Months Ended	3 Months Ended								12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 07, 2008	Sep. 08, 2008	Mar. 31, 2015	Dec. 31, 2011
Related Parties [Line Items]
Number of days of that liabilities exceed assets requiring FHFA to 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								$ 116,100,000,000
Capital Reserve Amount, current Year, Senior Preferred Stock Purchase Agreement, Amendment	2,400,000,000	2,400,000,000								2,400,000,000
Capital reserve amount for the next fiscal year based on the amended Senior Preferred Stock Purchase agreement	1,800,000,000	1,800,000,000								1,800,000,000
Annual reduction of capital reserve from 2013 to 2018 based on the Senior Preferred Stock Purchase Agreement, Amendment	600,000,000	600,000,000								600,000,000
Capital reserve amount on January 2018	0	0								0
Payment Of Cash Dividends On Senior Preferred Stock To Treasury	4,000,000,000									20,594,000,000	82,452,000,000	11,608,000,000
Net worth (deficit)	3,720,000,000	3,720,000,000				9,591,000,000				3,720,000,000	9,591,000,000	7,224,000,000				(4,571,000,000)
Percentage of common shares attributable to warrants issued to Treasury as a percentage to total diluted common shares upon exercise of the right	79.90%	79.90%								79.90%
Home Affordable Modification Program administrative expense reimbursements										71,000,000	92,000,000	96,000,000
Income Taxes Paid										2,815,000,000	2,350,000,000	0
Interest receivable	8,193,000,000	8,193,000,000				8,319,000,000				8,193,000,000	8,319,000,000
Capital Loss Carryforward, Valuation Allowance 1						525,000,000					525,000,000
Fee and other income		323,000,000	826,000,000	383,000,000	4,355,000,000	2,136,000,000	741,000,000	485,000,000	568,000,000	5,887,000,000	3,930,000,000	1,487,000,000
Change in Accounting Estimate [Abstract]
Fair value of guaranty obligation	797,000,000	797,000,000				1,100,000,000				797,000,000	1,100,000,000
Reserve for Guaranty Losses	1,200,000,000	1,200,000,000				1,400,000,000				1,200,000,000	1,400,000,000
Maximum term of early lender funding advances										60 days
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount											(58,300,000,000)	(5,300,000,000)
Private Label Securities Settlements [Member]
Related Parties [Line Items]
Fee and other income										4,800,000,000
Single-Family Individually Impaired Loan Loss Models Update [Member]
Related Parties [Line Items]
Allowance for Loan and Lease Losses, Period Increase (Decrease)			600,000,000					2,200,000,000
Series 2008-2 Senior Preferred Stock [Member]
Related Parties [Line Items]
Shares of variable liquidation preference senior preferred stock issued													1,000,000
Aggregate liquidation preference of senior preferred stock														1,000,000,000
US Treasury [Member]
Related Parties [Line Items]
Aggregate funding received from US Treasury pursuant to the senior preferred stock purchase agreement	116,100,000,000	116,100,000,000				116,100,000,000				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								1,000,000,000
Aggregate liquidation preference of senior preferred stock	117,100,000,000	117,100,000,000								117,100,000,000
Total remaining funding available from US Treasury pursuant to the senior preferred stock agreement	117,600,000,000	117,600,000,000								117,600,000,000
Capital Reserve Amount, current Year, Senior Preferred Stock Purchase Agreement, Amendment	2,400,000,000	2,400,000,000				3,000,000,000				2,400,000,000	3,000,000,000
Capital reserve amount for the next fiscal year based on the amended Senior Preferred Stock Purchase agreement	1,800,000,000	1,800,000,000								1,800,000,000
Annual reduction of capital reserve from 2013 to 2018 based on the Senior Preferred Stock Purchase Agreement, Amendment	600,000,000	600,000,000								600,000,000
Percentage of common shares attributable to warrants issued to Treasury as a percentage to total diluted common shares upon exercise of the right	79.90%	79.90%								79.90%			79.90%
Common stock warrant exercise price per share													0.00001
Fair value of the warrant at issuance														3,500,000,000
Percentage of initial principal loss US Treasury will bear for Temporary Credit and Liquidity Facilities and New Issue Bond Programs	35.00%	35.00%								35.00%
Loss of principal or interest under Treasury's Temporary Credit and Liquid Facilities and New Issue Bond Programs	0	0								0
Increase of Guarantee Fee Rate Resulting from the Temporary Payroll Tax Cut Continuation Act of 2011.	0.10%	0.10%								0.10%
TCCA fees		367,000,000	351,000,000	335,000,000	322,000,000	306,000,000	276,000,000	233,000,000	186,000,000	1,375,000,000	1,001,000,000	238,000,000
TCCA guaranty fee remitted										1,300,000,000	829,000,000	104,000,000
US Treasury [Member] | Temporary Credit and Liquidity Facilities Program [Member]
Related Parties [Line Items]
Principal and interest outstanding	390,000,000	390,000,000				821,000,000				390,000,000	821,000,000
US Treasury [Member] | New Issue Bond [Member]
Related Parties [Line Items]
Principal and interest outstanding	4,200,000,000	4,200,000,000				4,500,000,000				4,200,000,000	4,500,000,000
Freddie Mac [Member] | Freddie Mac [Member]
Related Parties [Line Items]
Fair value of mortgage-backed securities	6,900,000,000	6,900,000,000				8,700,000,000				6,900,000,000	8,700,000,000
Interest receivable	26,000,000	26,000,000				35,000,000				26,000,000	35,000,000
Investment income, interest										283,000,000	387,000,000	551,000,000
Federal Housing Finance Agency [Member]
Related Parties [Line Items]
FHFA assessment fees/expense										108,000,000	109,000,000	91,000,000
Common Securitization Solutions [Member]
Related Parties [Line Items]
Payments to Acquire Equity Method Investments										43,000,000
Scenario, Forecast [Member]
Related Parties [Line Items]
Undeclared Dividends On Senior Preferred Stock Next Quarter															$ 1,900,000,000