Financial Instruments (Offsetting of Financial Assets and Financial Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Offsetting of Assets
Gross Amounts of Recognized Assets	$ 365	$ 569
Gross Amounts Offset in the Consolidated Balance Sheets	(21)	(56)
Net Presented in the Consolidated Balance Sheets	344	513
Financial Instruments	(88)	(90)
Cash Collateral Received	(234)	(307)
Non-Cash Collateral Received	0	(14)
Net Assets Exposed	22	102
Offsetting of Liabilities
Gross Amounts of Recognized Liabilities	390	289
Gross Amounts Offset in the Consolidated Balance Sheets	(21)	(56)
Net Presented in the Consolidated Balance Sheets	369	233
Financial Instruments	(88)	(90)
Cash Collateral Pledged	0	0
Non-Cash Collateral Pledged	0	0
Net Liabilities	$ 281	$ 143