Commitments and Contingencies - Future Minimum Rental Commitments (Details) $ in Millions	Dec. 31, 2017 USD ($)
Future minimum rental commitments
Rent commitment, 2018	$ 122
Rent commitment, 2019	109
Rent commitment, 2020	83
Rent commitment, 2021	71
Rent commitment, 2022	69
Rent commitment, 2023 and beyond	516
Rent commitment, Total	970
Sublease income, 2018	(17)
Sublease income, 2019	(17)
Sublease income, 2020	(3)
Sublease income, 2021	0
Sublease income, 2022	0
Sublease income, 2023 and beyond	0
Sublease income, Total	(37)
Net rent, 2018	105
Net rent, 2019	92
Net rent, 2020	80
Net rent, 2021	71
Net rent, 2022	69
Net rent, 2023 and beyond	516
Net rent, Total	$ 933

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Operating Leases Future Minimum Net Payments Due.

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Operating leases future minimum net payments due current.

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Operating leases future minimum net payments due in five years.

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Operating leases future minimum net payments due in four years.

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Operating leases future minimum net payments due in three years.

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Operating leases future minimum net payments due in two years.

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Operating leases future minimum net payments due thereafter.

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Operating leases future minimum sublease income due current.

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Operating leases future minimum sublease income due in five years.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Contractually required future rental payments receivable on noncancelable subleasing arrangements.

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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 fifth 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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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 fourth 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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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 third 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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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 second 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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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due after the fifth 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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