Fair Value Measurements (Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets:
Deferred compensation plan assets	$ 68	$ 85
Investment in affiliate	67	187
Contingent consideration		91
Total assets	184	395
Liabilities:
Total recurring fair value measurements	119	375
Investment in affiliate	67	187
Commodity price derivatives | Other assets - noncurrent | Derivatives not designated as hedging instruments
Liabilities:
Fair Value		91
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Deferred compensation plan assets	68	85
Investment in affiliate	67	187
Contingent consideration		0
Total assets	135	272
Liabilities:
Total recurring fair value measurements	135	272
Investment in affiliate	67	187
Significant Other Observable Inputs (Level 2)
Assets:
Deferred compensation plan assets	0	0
Investment in affiliate	0	0
Contingent consideration		91
Total assets	49	123
Liabilities:
Total recurring fair value measurements	(16)	103
Investment in affiliate	0	0
Significant Unobservable Inputs (Level 3)
Assets:
Deferred compensation plan assets	0	0
Investment in affiliate	0	0
Contingent consideration		0
Total assets	0	0
Liabilities:
Total recurring fair value measurements	0	0
Investment in affiliate	0	0
Commodity price derivatives
Assets:
Commodity price derivatives	49	32
Liabilities:
Commodity price derivatives	65	20
Commodity price derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Commodity price derivatives	0	0
Liabilities:
Commodity price derivatives	0	0
Commodity price derivatives | Significant Other Observable Inputs (Level 2)
Assets:
Commodity price derivatives	49	32
Liabilities:
Commodity price derivatives	65	20
Commodity price derivatives | Significant Unobservable Inputs (Level 3)
Assets:
Commodity price derivatives	0	0
Liabilities:
Commodity price derivatives	$ 0	$ 0