Summary of Significant Accounting Policies Narratives(Details) (USD $)	0 Months Ended	3 Months Ended										3 Months Ended			3 Months Ended
	Mar. 29, 2013	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 US Treasury [Member]	Dec. 31, 2009 US Treasury [Member]	Mar. 31, 2013 US Treasury [Member] Temporary Credit and Liquidity Facilities Program [Member]	Dec. 31, 2012 US Treasury [Member] Temporary Credit and Liquidity Facilities Program [Member]	Mar. 31, 2013 US Treasury [Member] New Issue Bond [Member]	Dec. 31, 2012 US Treasury [Member] New Issue Bond [Member]	Mar. 31, 2013 Freddie Mac [Member]	Mar. 31, 2012 Freddie Mac [Member]	Dec. 31, 2012 Freddie Mac [Member]	Mar. 31, 2013 Single-Family [Member]		Mar. 31, 2013 Single-Family [Member] US Treasury [Member]
Related Parties [Line Items]
Deficit of core capital over statutory minimum capital requirement		$ 88,300,000,000			$ 141,200,000,000
Expected undeclared dividends payable on senior preferred stock for the next quarter		59,368,000,000
Deficit of core capital over statutory, minimum capital requirement, pro-forma basis		147,700,000,000
Number of days 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	75,200,000,000
Initial aggregate liquidation preference of senior preferred stock held by US Treasury						1,000,000,000
Aggregate liquidation preference of senior preferred stock						117,100,000,000
Maximum commitment from US Treasury pursuant to the senior preferred stock purchase agreement						200,000,000,000
Net worth		62,368,000,000			7,224,000,000
Total available funding from US Treasury pursuant to the senior preferred stock agreement after 2012						117,600,000,000
Senior preferred stock dividend rate in effect through December 31, 2012				10.00%
Capital reserve amount for 2013 per the senior preferred stock purchase agreement amendment		3,000,000,000
Annual reduction of capital reserve from 2013 to 2018 based on Senior Preferred Stock Purchase Agreement Amendment		600,000,000
Dividends declared on senior preferred stock		4,224,000,000
Payments of cash dividends on senior preferred stock to Treasury	4,224,000,000	4,224,000,000		2,819,000,000
Net worth on a proforma basis adjusted by expected undeclared dividends to be paid in the next quarter		3,000,000,000
Percentage of common shares attributable to warrants issued to US Treasury as percentage to total diluted common shares						79.90%
Home Affordable Modification Program administrative expense reimbursements from Treasury and Freddie Mac		26,000,000		22,000,000
Principal and interest outstanding								1,400,000,000	1,600,000,000	5,800,000,000	6,100,000,000
Percentage of initial principal loss US Treasury will bear for Temporary Credit and Liquidity Facilities and New Issue Bond Programs						35.00%
Loss of principal or interest under Treasury's Temporary Credit and Liquidity Facility and New Issue Bond Programs						0
Temporary Payroll Tax Cut related guaranty fee recorded in the Income Statement																	186,000,000
Temporary Payroll Tax Cut related guaranty fee paid to US Treasury																	134,000,000
Fair value of mortgage-backed securities												12,000,000,000		12,200,000,000
Interest receivable		9,160,000,000			9,176,000,000							48,000,000		51,000,000
Investment income, interest												111,000,000	153,000,000
Change in Accounting Estimate [Abstract]
Capital loss carryforwards, valuation allowance		491,000,000
Benefit for federal income taxes		$ 50,571,000,000	[1]	$ 0											$ 31,578,000,000	[1]

[1] Represents the release of the valuation allowance for our deferred tax assets that primarily are directly attributable to each segment based on the nature of the item.