Accumulated Other Comprehensive Income/(Loss) - Schedule of Amounts Reclassified out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification of actuarial losses from AOCI	$ 2,272			$ 0			$ 7,325	$ 0
Income from operations before income tax expense and equity in earnings of affiliated companies	11,106			31,886			12,830	94,046
Tax impact	(2,250)			(7,767)			(4,006)	(26,515)
Net income	8,997	$ (17,780)	$ 18,032	24,253	$ 24,748	$ 18,954	9,250	67,955
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from operations before income tax expense and equity in earnings of affiliated companies	2,272			0			7,325	0
Tax impact	(919)			0			(2,598)	0
Net income	1,354			0			4,726	0
Reclassification out of Accumulated Other Comprehensive Income | Accumulated defined benefit plans adjustment, net gain (loss) attributable to parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification of actuarial losses from AOCI	$ 2,272			$ 0			$ 7,325	$ 0