Accumulated Other Comprehensive Loss - Schedule of Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period			$ 304,506
Balance at end of period	$ 308,619		308,619
Currency Translation
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(178,597)	$ (170,739)	(172,843)	$ (172,434)
Other comprehensive income (loss)	2,426	(4,500)	(3,328)	(2,805)
Balance at end of period	(176,171)	(175,239)	(176,171)	(175,239)
Accumulated Defined Benefit Plans Adjustment | Defined Benefit Pension Plans
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(76,183)	(73,641)	(78,257)	(75,286)
Other comprehensive income (loss)	1,075	818	3,149	2,463
Balance at end of period	(75,108)	(72,823)	(75,108)	(72,823)
Accumulated Defined Benefit Plans Adjustment | OPEB
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(741)	(685)	(590)	(550)
Other comprehensive income (loss)	(70)	(65)	(221)	(200)
Balance at end of period	(811)	(750)	(811)	(750)
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(255,521)	(245,065)	(251,690)	(248,270)
Other comprehensive income (loss)	3,431	(3,747)	(400)	(542)
Balance at end of period	$ (252,090)	$ (248,812)	$ (252,090)	$ (248,812)