Concentrations of Credit Risk Estimated Benefit from Mortgage Insurance (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Risks and Uncertainties [Abstract]
Contractual mortgage insurance benefit	$ 4,491		$ 6,751
Less: Collectability adjustment	286	[1]	431	[1]
Estimated benefit included in total loss reserves	$ 4,205		$ 6,320

[1] Represents an adjustment that reduces the contractual benefit for our assessment of our mortgage insurer counterparties’ inability to fully pay the contractual mortgage insurance claims.