CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract]
Net income	$ 27,386	$ 38,122	$ 69,174	$ 106,561
Unrealized gain (loss) on defined benefit plan, net of tax	288	(6,553)	(6,563)	(11,562)
Unrealized gain (loss) on swaps and collars, net of tax	212	259	(409)	(3,146)
Unrealized foreign currency gain (loss), net of tax	20,887	(9,186)	18,006	(11,151)
Comprehensive income	48,773	22,642	80,208	80,702
Less: Comprehensive income attributable to noncontrolling interest	(234)	(62)	(821)	(501)
Total comprehensive income attributable to common stockholders	$ 48,539	$ 22,580	$ 79,387	$ 80,201