Leases Leases (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets and Liabilities, Lessee [Abstract]
ROU asset	$ 1,488
Lease liability	1,654
Cash paid for amounts included in the measurement of lease liability - operating cash flows	285
ROU assets obtained in exchange for new lease liabilities	$ 341	$ 0	$ 0
Weighted-average remaining lease term	8 years
Weighted-average discount rate	3.30%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 285
2021	266
2022	229
2023	213
2024	193
Thereafter	716
Total undiscounted cash flows	1,902
Less: interest	248
Lease liability	$ 1,654

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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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, due in third fiscal year following latest fiscal year.

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

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

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Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

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Weighted average discount rate for operating lease calculated at point in time.

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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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Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

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