Financial Guarantees Risk Characteristics - Single-Family (Details) (Single-Family [Member])	Dec. 31, 2013		Dec. 31, 2012
Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	100.00%	[1],[2]	100.00%	[1],[2]
Seriously delinquent, percentage (loan count)	2.38%	[3],[4],[5]	3.29%	[3],[4],[5]
Percentage of loans with detailed loan level information	99.00%		99.00%
Guaranty Book of Business [Member] | Conventional Loan [Member] | 2005 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	4.00%	[3],[6]	5.00%	[3],[6]
Seriously delinquent, percentage (loan count)	7.26%	[3],[5],[7]	7.79%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | 2006 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	3.00%	[3],[6]	5.00%	[3],[6]
Seriously delinquent, percentage (loan count)	11.26%	[3],[5],[7]	12.15%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | 2007 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	5.00%	[3],[6]	7.00%	[3],[6]
Seriously delinquent, percentage (loan count)	12.18%	[3],[5],[7]	12.99%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | 2008 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	3.00%	[3],[6]	5.00%	[3],[6]
Seriously delinquent, percentage (loan count)	6.69%	[3],[5],[7]	6.63%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | All Other Vintages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	85.00%	[3],[6]	78.00%	[3],[6]
Seriously delinquent, percentage (loan count)	1.02%	[3],[5],[7]	1.36%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | Alt-A [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	5.00%	[3],[6]	6.00%	[3],[6]
Seriously delinquent, percentage (loan count)	9.23%	[3],[5],[7]	11.36%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | Subprime [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Seriously delinquent, percentage (loan count)	16.93%	[3],[5],[7]	20.60%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | California
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	20.00%	[3],[6]	19.00%	[3],[6]
Seriously delinquent, percentage (loan count)	0.98%	[3],[5],[7]	1.69%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | Florida
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	6.00%	[3],[6]	6.00%	[3],[6]
Seriously delinquent, percentage (loan count)	6.89%	[3],[5],[7]	10.06%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | Illinois
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	4.00%	[3],[6]	4.00%	[3],[6]
Seriously delinquent, percentage (loan count)	3.12%	[3],[5],[7]	4.70%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | New Jersey
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	4.00%	[3],[6]	4.00%	[3],[6]
Seriously delinquent, percentage (loan count)	6.25%	[3],[5],[7]	6.92%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | New York
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	5.00%	[3],[6]	6.00%	[3],[6]
Seriously delinquent, percentage (loan count)	4.42%	[3],[5],[7]	4.70%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | All Other States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	61.00%	[3],[6]	61.00%	[3],[6]
Seriously delinquent, percentage (loan count)	1.85%	[3],[5],[7]	2.56%	[3],[5],[7]
Guaranty Book of Business [Member] | Conventional Loan [Member] | Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 100% [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	7.00%	[3],[6]	13.00%	[3],[6]
Seriously delinquent, percentage (loan count)	12.22%	[3],[5],[7]	13.42%	[3],[5],[7]
Maximum [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member] | Subprime [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	0.50%	[3],[6],[8]	0.50%	[3],[6],[8]
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Serious delinquency, days past due	90 days		90 days
Minimum [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of loans with detailed loan level information	99.00%		99.00%
Original LTV Ratio Greater Than 90% and FICO Score Less Than 620 [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	1.00%	[3],[6]	1.00%	[3],[6]
Seriously delinquent, percentage (loan count)	10.90%	[3],[5],[7]	14.76%	[3],[5],[7]

[1] Consists of the portion of our single-family conventional guaranty book of business for which we have detailed loan level information, which constituted over 99% of our total single-family conventional guaranty book of business as of December 31, 2013 and 2012.

[2] Midwest consists of IL, IN, IA, MI, MN, NE, ND, OH, SD, WI; Northeast consists of CT, DE, ME, MA, NH, NJ, NY, PA, PR, RI, VT, VI; Southeast consists of AL, DC, FL, GA, KY, MD, MS, NC, SC, TN, VA, WV; Southwest consists of AZ, AR, CO, KS, LA, MO, NM, OK, TX, UT; West consists of AK, CA, GU, HI, ID, MT, NV, OR, WA and WY.

[3] Consists of the portion of our single-family conventional guaranty book of business for which we have detailed loan level information, which constituted approximately 99% of our total single-family conventional guaranty book of business as of December 31, 2013 and 2012.

[4] Calculated based on the number of single-family conventional loans that were delinquent divided by the total number of loans in our single-family conventional guaranty book of business.

[5] Consists of single-family conventional loans that were 90 days or more past due or in the foreclosure process as of December 31, 2013 and 2012.

[6] Calculated based on the aggregate unpaid principal balance of single-family conventional loans for each category divided by the aggregate unpaid principal balance of loans in our single-family conventional guaranty book of business.

[7] Calculated based on the number of single-family conventional loans that were seriously delinquent divided by the total number of single-family conventional loans for each category included in our guaranty book of business.

[8] Represents less than 0.5% of the single-family conventional guaranty book of business.