Outstanding Exposure - Surveillance Categories and Debt Service Outstanding (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Financial guarantee obligations
Minimum amount assumed principal amount for internal rating	$ 1,000,000
Constant discount rate (as a percent)	5.00%
Probability of paying more claims than being reimbursed (as a percent)	50.00%
Maximum period of liquidity claims (in years)	1 year
Gross debt service outstanding	672,048,000,000	737,380,000,000
Net debt service outstanding	631,453,000,000	690,535,000,000
Mortgage guaranty insurance	140,000,000
Public finance
Financial guarantee obligations
Gross debt service outstanding	605,569,000,000	650,924,000,000
Net debt service outstanding	569,974,000,000	610,011,000,000
Structured finance
Financial guarantee obligations
Gross debt service outstanding	66,479,000,000	86,456,000,000
Net debt service outstanding	$ 61,479,000,000	$ 80,524,000,000