Contracts Accounted for as Credit Derivatives - Credit Derivatives Subordination and Ratings (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	$ 7,535	$ 16,997
Collateralized Debt Obligations [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,644	10,425
Collateralized Debt Obligations [Member] | CLO/collateralized bond obligations [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	199	2,022
Collateralized Debt Obligations [Member] | Synthetic investment grade pooled corporate [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	547	7,224
Collateralized Debt Obligations [Member] | TruPS CDOs [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	898	1,179
RMBS [Member] | United States [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,003	1,142
Pooled Infrastructure Transactions [Member] | United States [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,553	1,513
Infrastructure Finance [Member] | United States [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	847	1,021
Other [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	$ 2,488	$ 2,896