Outstanding Exposure - Schedule of Non-Financial Guaranty Exposure (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Capital relief triple-X life insurance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Exposure	$ 880	$ 773
Net debt service outstanding	763	675
Aircraft residual value insurance policies [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Exposure	340	201
Net debt service outstanding	$ 218	$ 140