Leases, Additional Information (Details) $ in Millions	Mar. 31, 2019 USD ($)
ROU assets, net reflected in the following balance sheet line items:
Operating lease ROU assets, net, balance sheet line item	us-gaap:OtherAssetsNoncurrent
Operating leases - deferred charges and other assets, net	$ 1,303
Current lease liabilities reflected in the following balance sheet line items:
Current operating lease liabilities, balance sheet line item	us-gaap:AccruedLiabilitiesCurrent
Operating leases - accrued expenses	$ 304
Noncurrent lease liabilities reflected in the following balance sheet line items:
Noncurrent operating lease liabilities, balance sheet line item	us-gaap:OtherLiabilitiesNoncurrent
Operating leases - other long-term liabilities	$ 956
Total lease liabilities	$ 1,260
ROU assets, net reflected in the following balance sheet line items:
Finance lease ROU assets, net, balance sheet line item	us-gaap:PropertyPlantAndEquipmentNet
Finance leases - property, plant, and equipment, net	$ 597
Current lease liabilities reflected in the following balance sheet line items:
Current finance lease liabilities, balance sheet line item	us-gaap:DebtCurrent
Finance leases - current portion of debt and finance lease obligations	$ 25
Noncurrent lease liabilities reflected in the following balance sheet line items:
Noncurrent finance lease liabilities, balance sheet line item	us-gaap:LongTermDebtAndCapitalLeaseObligations
Finance leases - debt and finance lease obligations, less current portion	$ 581
Total lease liabilities	$ 606
Operating Leases
Weighted-average remaining lease term	8 years 3 months 18 days
Weighted-average discount rate	5.10%
Finance Leases
Weighted-average remaining lease term	23 years 3 months 18 days
Weighted-average discount rate	5.50%