CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract]
Net income	$ 154,115	$ 105,406	$ 266
Unrealized (loss) gain on defined benefit plan, net of tax	(4,142)	3,440	(4,897)
Unrealized (loss) gain on interest rate swap, net of tax	(3,652)	737	1,018
Unrealized foreign currency gain (loss), net of tax	1,501	(22,543)	33,065
Comprehensive income	147,822	87,040	29,452
Less: Comprehensive income attributable to noncontrolling interest	(865)	(1,385)	(2,071)
Total comprehensive income attributable to common stockholders	$ 146,957	$ 85,655	$ 27,381