Employee Benefits - Estimated Future Benefit Payments (Details) - Pension Plan $ in Millions	Dec. 31, 2018 USD ($)
U.K.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2019	$ 137
2020	139
2021	144
2022	149
2023	152
2024 - 2028	795
U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2019	178
2020	182
2021	185
2022	187
2023	177
2024 - 2028	879
Other
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2019	42
2020	43
2021	44
2022	45
2023	46
2024 - 2028	$ 248

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in fourth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in third fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

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