Derivative Financial Instruments (Financial Statement Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	$ (244)	$ (256)	$ (244)	$ (256)
Derivative, Gain (Loss) Recognized	25	$ (1)	47	$ (4)
Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	$ (244)		$ (244)		$ (250)