Financial Guarantees Delinquency Status - Multifamily (Details) (Multifamily [Member])	Dec. 31, 2013		Dec. 31, 2012
Guaranty Book of Business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30 days delinquent, percentage (unpaid principal balance)	0.03%	[1],[2]	0.23%	[1],[2]
Seriously delinquent, percentage (unpaid principal balance)	0.10%	[1],[2],[3]	0.24%	[1],[2],[3]
Percentage of loans with detailed loan level information	99.00%		99.00%
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Serious delinquency, days past due	60 days		60 days
Original Debt Service Coverage Ratio Less Than or Equal to 1.1 [Member] | Guaranty Book of Business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Seriously delinquent, percentage (loan count)			0.22%	[1],[3],[4]
Original Debt Service Coverage Ratio Less Than or Equal to 1.1 [Member] | Maximum [Member] | Guaranty Book of Business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Seriously delinquent, percentage (loan count)	0.005%	[1],[3],[4],[5]

[1] Consists of the portion of our multifamily guaranty book of business for which we have detailed loan level information, which constituted approximately 99% of our total multifamily guaranty book of business as of December 31, 2013 and 2012, excluding loans that have been defeased.

[2] Calculated based on the aggregate unpaid principal balance of multifamily loans for each category divided by the aggregate unpaid principal balance of loans in our multifamily guaranty book of business.

[3] Consists of multifamily loans that were 60 days or more past due as of the dates indicated.

[4] Calculated based on the unpaid principal balance of multifamily loans that were seriously delinquent divided by the aggregate unpaid principal balance of multifamily loans for each category included in our guaranty book of business.

[5] Represents a serious delinquency rate of less than 0.005%.