CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract]
Net income	$ 20,400	$ 31,736
Unrealized gain (loss) on defined benefit plan, net of tax	9,719	(6,029)
Unrealized loss on swaps and collars, net of tax	(1,438)	(3,909)
Unrealized foreign currency (loss) gain, net of tax	(9,614)	4,936
Comprehensive income	19,067	26,734
Less: Comprehensive income attributable to noncontrolling interest	(232)	(20)
Total comprehensive income attributable to common stockholders	$ 18,835	$ 26,714