Segment Reporting - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Energy Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,005	$ 1,622	$ 2,811	$ 4,794
Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	660	744	1,882	2,181
Petroleum products | Energy Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	926	1,533	2,551	4,476
Nitrogen fertilizer products | Energy Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	79	89	260	318
Automotive services | Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	327	356	913	1,028
Aftermarket parts sales | Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 333	$ 388	$ 969	$ 1,153