Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Offsetting [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 57	$ 41
Derivative Asset, Fair Value, Gross Liability	0	0
Net amounts of assets presented on the Condensed Consolidated Balance Sheet	57	41
Derivative Asset, Financial Instruments Not Offset	(2)	0
Derivative, Collateral, Obligation to Return Cash	(54)	(4)
Derivative Assets in Net Asset Position	1	37
Derivative Assets With No Offsetting Arrangements	2
No amount offset on Balance Sheet	0
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	59	41
Derivative Asset Fair Value Gross Asset Including Not Subject To Master Netting Arrangement Not Offset Against Collateral	59	41
Derivative Asset	3	37
Derivative Liability, Fair Value, Gross Liability	2	37
Derivative Liability, Gross Amount Offset in the Condensed Consolidated Balance Sheet	0	0
Net Amounts of Liabilities Presented on the Condensed Consolidated Balance Sheet	2	37
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	0	0
Derivative Liabilities, Collateral Amounts Not Offset	(1)	0
Derivative Liability	1	37
Derivative Liability, Net Asset Position	2
Derivative Liability in Net Asset Position, Gross Amounts Offset	0
Derivative Liability in Net Asset Position, Gross Amounts Not Offset on Balance Sheet, Financial Instruments	(2)
Derivative Liability in Net Asset Position, Gross Amounts Not Offset on Balance Sheet, Collateral	0
Derivative Liability, Net Asset Position, Net Amount	0
Fair value of derivative contracts in payable position	4	37
Derivative Liabilities, Financial Instruments Not Offset	(2)	0
Securities Sold under Agreements to Repurchase, Gross Amounts Recognized	432	685
Securities Sold under Agreements to Repurchase, Gross Amounts Offset	0	0
Securities Sold under Agreements to Repurchase, Net Amounts Presented	432	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	(432)	(685)
Securities Sold Under Agreements to Repurchase, Net Amount	0	0
Total liabilities, gross amounts recognized	436	722
Total liabilities, net amounts presented on the balance sheet	436	722
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Collateral, Right to Reclaim Cash	(433)	(685)
Securities Purchased under Agreements to Resell, Fair Value of Collateral	1	4
Customer Securities for which Entity has Right to Sell or Repledge, Fair Value	33	7
Derivative Asset, Fair Value of Collateral	$ 32	$ 3