Contracts Accounted for as Insurance - Reconciliation of Net Expected Loss to be Paid and Expensed (Details) - USD ($) $ in Millions		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Guarantor Obligations [Line Items]
Net expected loss to be paid (recovered) after recoveries for R&W		$ (1,198)	[1]	$ (1,391)	[1]	$ (1,169)
Contra-paid, net	[2],[3]	37		6
Loss and LAE reserve - financial guaranty insurance contracts, net of reinsurance	[4]	(1,047)		(998)
Other recoverable (payable)		(1)		3
Net expected loss to be expensed (present value)		421
Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Net expected loss to be expensed (present value)		64
Financial Guarantee Insurance And Other Product Line [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid (recovered) after recoveries for R&W	[5]	1,083
Contra-paid, net		37
Salvage and subrogation recoverable, net of reinsurance		348
Loss and LAE reserve - financial guaranty insurance contracts, net of reinsurance		(1,046)
Other recoverable (payable)		(1)
Net expected loss to be expensed (present value)	[6]	421
Financial Guarantee Insurance And Other Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Loss and LAE reserve - financial guaranty insurance contracts, net of reinsurance		$ 64		$ 74

[1] Includes expected LAE to be paid of $12 million as of December 31, 2016 and $12 million as of December 31, 2015.

[2] Excludes $90 million and $110 million of deferred premium revenue and $25 million and $30 million of contra-paid related to FG VIEs as of December 31, 2016 and December 31, 2015, respectively.

[3] See "Financial Guaranty Insurance Losses – Insurance Contracts' Loss Information" below for an explanation of "contra-paid".

[4] See “Components of Net Reserves (Salvage)” table for loss and LAE reserve and salvage and subrogation recoverable components.

[5] See "Net Expected Loss to be Paid (Recovered) by Accounting Model" table in Note 5, Expected Loss to be Paid.

[6] Excludes $64 million as of December 31, 2016 related to consolidated FG VIEs.