Pension and Other Postretirement Benefits - Contributions for Pension and Other Postretirement Benefits (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Other Postretirement Benefit Plans [Member]
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Contribution	$ 469	$ 966
U.S. [Member] | Defined Benefit Pension Plan [Member]
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Contribution	0	281
U.S. [Member] | Defined Contribution Plan [Member]
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Contribution	2,320	2,296
Foreign Defined Benefits Pension Plans [Member] | Defined Benefit Pension Plan [Member]
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Contribution	483	332
U.K. [Member] | Defined Benefit Pension Plan [Member]
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Contribution	$ 248	$ 222