Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Offsetting [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 91	$ 41
Derivative Asset, Fair Value, Gross Liability		0
Net amounts of assets presented on the Condensed Consolidated Balance Sheet	91	41
Derivative Asset, Financial Instruments Not Offset	(2)	0
Derivative, Collateral, Obligation to Return Cash	(86)	(4)
Derivative Assets in Net Asset Position	3	37
Derivative Assets With No Offsetting Arrangements	3
Derivative Assets, Gross Amounts Offset on the Condensed Consolidated Balance Sheet	0
Derivative, Collateral, Obligation to Return Securities - No Offsetting Arrangements	0
Derivative, Collateral, Obligation to Return Cash - No Offsetting Arrangements	0
No amount offset on Balance Sheet	0
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	94	41
Derivative Asset Fair Value Gross Asset Including Not Subject To Master Netting Arrangement Not Offset Against Collateral	94	41
Derivative Asset	6	37
Derivative Liability, Fair Value, Gross Liability	1	37
Net Amounts of Liabilities Presented on the Condensed Consolidated Balance Sheet	1	37
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	0	0
Derivative Liabilities, Collateral Amounts Not Offset	(1)	0
Derivative, Net Liability Position, Aggregate Fair Value	0	37
Derivative Liability	1	37
Derivative Liability, Net Asset Position	1
Derivative Liabilities - Gross Amounts Offset on the Condensed Consolidated Balance Sheet	0	0
Derivative Liability in Net Asset Position, Gross Amounts Not Offset on Balance Sheet, Financial Instruments	(1)
Derivative Liability in Net Asset Position, Gross Amounts Not Offset on Balance Sheet, Collateral	0
Derivative Liability, Net Asset Position, Net Amount	0
Derivative Liability, Not Subject to Master Netting Arrangement	1
Fair value of derivative contracts in payable position	3	37
Derivative Liabilities, Financial Instruments Not Offset	(1)	0
Securities Sold under Agreements to Repurchase, Gross Amounts Recognized	459	685
Securities Sold under Agreements to Repurchase, Net Amounts Presented	459	685
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	0	0
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash	(459)	(685)
Securities Sold Under Agreements to Repurchase, Net Amount	0	0
Total liabilities, gross amounts recognized	462	722
Total liabilities, net amounts presented on the balance sheet	462	722
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Collateral, Right to Reclaim Cash	(460)	(685)
Securities Purchased under Agreements to Resell, Fair Value of Collateral		4
Customer Securities for which Entity has Right to Sell or Repledge, Fair Value	38	7
Derivative Asset, Fair Value of Collateral	$ 38	$ 3