Leases - Components of Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
ROU assets		$ 200
Lease liabilities	$ 156	$ 200
Finance lease cost
Amortization of ROU assets	4
Interest on lease liabilities	1
Operating lease cost	386
Short-term lease cost	9
Variable lease cost	128
Sublease income	(2)
Total lease cost	$ 526
Real estate
Lessee, Lease, Description [Line Items]
Average term (in years)	5 years
Equipment leases \| Minimum
Lessee, Lease, Description [Line Items]
Average term (in years)	2 years
Equipment leases \| Maximum
Lessee, Lease, Description [Line Items]
Average term (in years)	5 years
Property, plant and equipment
Lessee, Lease, Description [Line Items]
ROU assets	$ 149
Short-term debt
Lessee, Lease, Description [Line Items]
Lease liabilities	13
Long-term debt
Lessee, Lease, Description [Line Items]
Lease liabilities	$ 144

No definition available.

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- Definition

Amount of interest expense on finance lease liability.

+ References

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- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

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- Definition

Amount of lessee's right to use underlying asset under finance lease.

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- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

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- Definition

Amount of lease cost recognized by lessee for lease contract.

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- Definition

Term of lessee's finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

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- Definition

Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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Amount of sublease income excluding finance and operating lease expense.

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- Definition

Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

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