Financial Guarantees Risk Characteristics - Single-Family (Details) (Single-Family [Member])	6 Months Ended		12 Months Ended
	Jun. 30, 2014		Dec. 31, 2013
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%
Seriously delinquent, percentage (loan count)	2.05%	[1],[2],[3]	2.38%	[1],[2],[3]
2005 [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	3.00%	[1],[4]	4.00%	[1],[4]
Seriously delinquent, percentage (loan count)	6.47%	[1],[3],[5]	7.26%	[1],[3],[5]
2006 [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	3.00%	[1],[4]	3.00%	[1],[4]
Seriously delinquent, percentage (loan count)	10.11%	[1],[3],[5]	11.26%	[1],[3],[5]
2007 [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	4.00%	[1],[4]	5.00%	[1],[4]
Seriously delinquent, percentage (loan count)	11.08%	[1],[3],[5]	12.18%	[1],[3],[5]
2008 [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	3.00%	[1],[4]	3.00%	[1],[4]
Seriously delinquent, percentage (loan count)	6.27%	[1],[3],[5]	6.69%	[1],[3],[5]
All Other Vintages [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	87.00%	[1],[4]	85.00%	[1],[4]
Seriously delinquent, percentage (loan count)	0.91%	[1],[3],[5]	1.02%	[1],[3],[5]
Alt-A [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	4.00%	[1],[4]	5.00%	[1],[4]
Seriously delinquent, percentage (loan count)	8.37%	[1],[3],[5]	9.23%	[1],[3],[5]
Subprime [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Seriously delinquent, percentage (loan count)	15.65%	[1],[3],[5]	16.93%	[1],[3],[5]
California | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	20.00%	[1],[4]	20.00%	[1],[4]
Seriously delinquent, percentage (loan count)	0.77%	[1],[3],[5]	0.98%	[1],[3],[5]
Florida | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	6.00%	[1],[4]	6.00%	[1],[4]
Seriously delinquent, percentage (loan count)	5.46%	[1],[3],[5]	6.89%	[1],[3],[5]
Illinois | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	4.00%	[1],[4]	4.00%	[1],[4]
Seriously delinquent, percentage (loan count)	2.60%	[1],[3],[5]	3.12%	[1],[3],[5]
New Jersey | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	4.00%	[1],[4]	4.00%	[1],[4]
Seriously delinquent, percentage (loan count)	5.94%	[1],[3],[5]	6.25%	[1],[3],[5]
New York | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	5.00%	[1],[4]	5.00%	[1],[4]
Seriously delinquent, percentage (loan count)	4.24%	[1],[3],[5]	4.42%	[1],[3],[5]
All Other States [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	61.00%	[1],[4]	61.00%	[1],[4]
Seriously delinquent, percentage (loan count)	1.60%	[1],[3],[5]	1.85%	[1],[3],[5]
Original LTV Ratio Greater Than Ninety Percent and FICO Score Less Than Six Hundred Twenty [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	1.00%	[1],[4]	1.00%	[1],[4]
Seriously delinquent, percentage (loan count)	9.34%	[1],[3],[5]	10.90%	[1],[3],[5]
Estimated Mark-to-Market Loan-to-Value Ratio Greater Than 100% [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	6.00%	[1],[4]	7.00%	[1],[4]
Seriously delinquent, percentage (loan count)	11.40%	[1],[3],[5]	12.22%	[1],[3],[5]
Maximum [Member] | Subprime [Member] | Guaranty Book of Business [Member] | Conventional Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of book of business	0.50%	[1],[4],[6]	0.50%	[1],[4],[6]
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Serious delinquency, days past due	90 days		90 days

[1] 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 June 30, 2014 and December 31, 2013.

[2] 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.

[3] Consists of single-family conventional loans that were 90 days or more past due or in the foreclosure process as of June 30, 2014 and December 31, 2013.

[4] 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.

[5] 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.

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