Debt, Other Debt, Capital Lease Obligations, and Other Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Principal Payments Due on Debt
2019	$ 214
2020	855
2021	15
2022	5
2023	20
Thereafter	7,474
Net unamortized debt issuance costs and other	(80)	$ (73)
Total debt	8,503	8,310
Future Minimum Rentals on Capital Lease Obligations
2019	69
2020	65
2021	62
2022	64
2023	65
Thereafter	957
Total minimum lease payments	1,282
Less amount representing interest	676
Total capital lease obligations	606	562
Capital Lease Obligations [Member]
Capital Lease Obligations (Textual)
Capital lease obligations incurred	63	502
Assets Held under Capital Leases [Member]
Capital Lease Obligations (Textual)
Capital lease assets recognized	63	$ 502
Pure Biofuels [Member]
Other Debt (Textual)
Amount of debt retired	$ 137