Leases (Details) $ in Millions	6 Months Ended
Jun. 30, 2019 USD ($)
Assets and Liabilities, Lessee [Abstract]
ROU asset	$ 1,494
Lease liability	1,660
Cash paid for amounts included in the measurement of lease liability - operating cash flows	135
ROU assets obtained in exchange for new lease liabilities	$ 216
Weighted-average remaining lease term	8 years
Weighted-average discount rate	3.30%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remainder of 2019	$ 154
2020	274
2021	247
2022	213
2023	201
Thereafter	832
Total undiscounted cash flows	1,921
Less: interest	261
Lease liability	$ 1,660

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Amount of lessee's undiscounted obligation for lease payments for operating lease.

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Amount of lessee's undiscounted obligation for lease payments for operating lease, due after fifth fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments for operating lease having an initial or remaining lease term in excess of one year due in remainder of fiscal year following latest fiscal year.

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

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Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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