Leases (Operating Lease Agreements) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Gross Rental Commitments
2019	$ 361
2020	340
2021	277
2022	252
2023	214
Subsequent years	753
Rentals from Subleases
2019	32
2020	31
2021	12
2022	10
2023	9
Subsequent years	32
Net Rental Commitments
2019	329
2020	309
2021	265
2022	242
2023	205
Subsequent years	$ 721

Operating Leases Future Minimum Payments Due, Net of Sublease Receivable [Abstract]

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Operating Leases, Future Minimum Payments, Net of Sublease Receivable, Due In Four Years

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Future minimum lease payments receivable under operating leases for periods greater than five years following the balance sheet date.

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