Pensions and Postretirement Benefits Other than Pensions - Details of Activity in Investment in European Infrastructure and Property Funds (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Disbursements	$ (22,701)
United Kingdom plan
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plans’ assets at beginning of year		$ 383,831
Fair value of plans’ assets at end of year		347,108	$ 383,831
United Kingdom plan \| Significant Unobservable Inputs Level (3)
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plans’ assets at beginning of year		38,070	33,796	$ 27,062
Transfer into level 3		0	0	9,489
Disbursements		0	0	0
Change in fair value		(7,294)	969	3,545
Foreign currency translation effect		(1,838)	3,305	(6,300)
Fair value of plans’ assets at end of year		$ 28,938	$ 38,070	$ 33,796

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

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- Definition

Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) plan assets of defined benefit plan.

+ References

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- Definition

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan, for assets transferred into (out of) Level 3 of fair value hierarchy. Includes, but is not limited to, transfer due to change in observability of significant inputs.

+ References

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