Fair Value Measurement (Commodity Derivative Balances Subject to Right of Setoff) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Offsetting Derivative Assets [Abstract]
Assets - Gross Amounts Recognized	$ 1,243	$ 255
Assets - Amounts Not Subject to Right of Setoff	85	2
Assets - Amounts Subject to Right of Setoff, Gross Amounts	1,158	253
Assets - Amounts Subject to Right of Setoff, Gross Amounts Offset	650	157
Assets - Amounts Subject to Right of Setoff, Net Amounts Presented	508	96
Assets - Amounts Subject to Right of Setoff, Cash Collateral	0	10
Assets - Amounts Subject to Right of Setoff, Net Amounts	508	86
Offsetting Derivative Liabilities [Abstract]
Liabilities - Gross Amounts Recognized	1,223	220
Liabilities - Amounts Not Subject to Right of Setoff	82	1
Liabilities - Amounts Subject to Right of Setoff, Gross Amounts	1,141	219
Liabilities - Amounts Subject to Right of Setoff, Gross Amounts Offset	650	157
Liabilities - Amounts Subject to Right of Setoff, Net Amounts Presented	491	62
Liabilities - Amounts Subject to Right of Setoff, Cash Collateral	36	4
Liabilities - Amounts Subject to Right of Setoff, Net Amounts	$ 455	$ 58