Commitments and Contingencies (Unaudited) (Details) £ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) Rate	Mar. 31, 2017 USD ($)	Mar. 31, 2018 GBP (£)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Site Contingency [Line Items]
Accrual for Environmental Remediation Costs				$ 416,000,000	$ 410,000,000
Recorded Third-Party Environmental Recoveries, Amount				211,000,000	207,000,000
Financial Arrangements
Standby Unused Letters Of Credit and bank guarantees				192,000,000
Surety Bond Outstanding				196,000,000
Operating leases
Rental expense for operating leases, net of immaterial amounts of sublease rental income	$ 92,000,000	$ 89,000,000
Line of Credit Facility [Line Items]
Debt Instrument, Covenant Compliance	the company was in compliance with all covenants under its credit agreements.
Two Year Term [Member] [Domain]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			£ 120	170,000,000
Line of Credit Outstanding			£ 90	127,000,000
Five Year Term [Member] [Domain]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				1,600,000,000
Line of Credit Outstanding				0
Other Current Liabilities [Member]
Site Contingency [Line Items]
Accrual for Environmental Remediation Costs				151,000,000
Other Noncurrent Liabilities [Member]
Site Contingency [Line Items]
Accrual for Environmental Remediation Costs				265,000,000
Other Current Assets [Member]
Site Contingency [Line Items]
Recorded Third-Party Environmental Recoveries, Amount				79,000,000
Other Noncurrent Assets [Member]
Site Contingency [Line Items]
Recorded Third-Party Environmental Recoveries, Amount				132,000,000
London Interbank Offered Rate (LIBOR) [Member] | Two Year Term [Member] [Domain]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate During Period | Rate	1.10%
Environmental Issue [Member] | Maximum
Site Contingency [Line Items]
Loss Contingency, Estimate of Possible Loss				789,000,000	792,000,000
Environmental Issue [Member] | Minimum
Site Contingency [Line Items]
Loss Contingency, Estimate of Possible Loss				$ 410,000,000	$ 405,000,000