Consolidated Statements of Shareholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Unrecognized Gains (Losses) on Derivative Instruments	Pension Obligations	Cumulative Translation Adjustment	Retained Earnings
Beginning of period at Dec. 31, 2018	$ 373,265	$ 87,723	$ (3,205)	$ (3,000)	$ (99,290)	$ 391,037
Beginning of the period (in shares) at Dec. 31, 2018		25,019,237
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(96,460)					(96,460)
Change in unrecognized gains/losses on derivative instruments, net of tax	13,156		13,156
Change in defined benefit plans, net of taxes	(2,571)			(2,571)
Net foreign currency translation adjustment	(5,168)				(5,168)
Common stock issued, net of shares withheld for employee taxes (in shares)		108,921
Stock-based compensation	5,608	$ 5,608
Cash dividend declared	(4,597)					(4,597)
Redeemable preferred 9% dividend, participating dividend and accretion	(30,977)					(30,977)
European non-controlling redeemable equity dividend	(566)					(566)
End of period at Dec. 31, 2019	$ 251,690	$ 93,331	9,951	(5,571)	(104,458)	258,437
End of the period (in shares) at Dec. 31, 2019	25,128,158	25,128,158
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ (243,561)					(243,561)
Change in unrecognized gains/losses on derivative instruments, net of tax	(11,689)		(11,689)
Change in defined benefit plans, net of taxes	(1,876)			(1,876)
Net foreign currency translation adjustment	14,197				14,197
Common stock issued, net of shares withheld for employee taxes (in shares)		463,772
Stock-based compensation	1,916	$ 1,916
Redeemable preferred 9% dividend, participating dividend and accretion	(31,994)					(31,994)
European non-controlling redeemable equity dividend	(205)					(205)
End of period at Dec. 31, 2020	$ (21,522)	$ 95,247	$ (1,738)	$ (7,447)	$ (90,261)	$ (17,323)
End of the period (in shares) at Dec. 31, 2020	25,591,930	25,591,930