Summary of Significant Accounting Policies - Leases (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Renewal term	20 years
Lease, option to terminate	60 days
Lease liability	$ 586
Right of use asset	483
Lease, cost	171
Variable lease, cost	$ 30
Weighted average remaining lease term (years)	6 years
Weighted average discount rate	3.15%
2020	$ 133
2021	121
2022	102
2023	84
2024	67
Thereafter	137
Total lease payments	644
Less: interest	(58)
Present value of lease liabilities	$ 586
Minimum
Lessee, Lease, Description [Line Items]
Lease, term of contract	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease, term of contract	10 years

Lessee, Operating Lease, Term of Contract, Option to Terminate

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- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
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- Definition

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.

+ References

No definition available.

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- Definition

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

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-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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

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- Definition

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

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- Definition

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

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- Definition

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

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- Definition

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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- 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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