Employee Benefit Plans - Additional Information (Detail) $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($)
North America
Defined Benefit Plan Disclosure [Line Items]
Pension and other postretirement contributions, current period	$ 1
Pension and other postretirement contributions, remainder of fiscal year	1
United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Pension and other postretirement contributions, current period	1
Pension and other postretirement contributions, remainder of fiscal year	$ 1

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration