Derivative Assets And Liabilities Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Total derivatives assets	$ 455	$ 384
Total derivatives liabilities	(1,043)	(788)
Designated as Hedging Instrument [Member] | Commodity derivatives (margin deposits)
Total derivatives assets	18	24
Total derivatives liabilities	(22)	0
Not Designated as Hedging Instrument [Member]
Total derivatives assets	437	360
Total derivatives liabilities	(1,021)	(788)
Not Designated as Hedging Instrument [Member] | Commodity derivatives (margin deposits)
Total derivatives assets	370	319
Total derivatives liabilities	(367)	(350)
Not Designated as Hedging Instrument [Member] | Commodity derivatives
Total derivatives assets	67	41
Total derivatives liabilities	(77)	(39)
Not Designated as Hedging Instrument [Member] | Interest rate derivatives
Total derivatives assets	0	0
Total derivatives liabilities	$ (577)	$ (399)