Fair Value of Financial Instruments - Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 5,179	$ 5,307
Level 2 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	5,113	5,218
Level 2 | Equity swap agreement | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	(1)
Level 2 | Equity swap agreement | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative asset		4
Derivative liability	(1)
Level 2 | Commodity contracts | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	0	(2)
Level 2 | Commodity contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	0	(2)
Other debt | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 192	$ 172