Accounts Payable and Other Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable and Other Current Liablities [Line Items]
Compensation and benefits payable	$ 857	$ 776
Accounts payable	309	487
Property and income tax liabilities	301	497
Accrued interest	289	300
Customer incentives	201	149
Capital expenditure estimated liabilities	167	202
Casualty and environmental liabilities	125	125
Rents and leases	109	117
Other	811	785
Total	$ 3,169	$ 3,438