Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 78,172	$ 30,955	$ 135,772	$ 77,696
Other comprehensive income (loss), net of tax:
Changes in net prior service credit and actuarial losses	1,809	2,614	2,748	5,120
Change in fair value of derivatives	104	(1,601)	(2,351)	(2,488)
Foreign currency translation	(1,576)	6,045	(38,015)	803
Other comprehensive income (loss)	337	7,058	(37,618)	3,435
Comprehensive income	$ 78,509	$ 38,013	$ 98,154	$ 81,131