Consolidated Statement of Shareholders' Equity - USD ($)	Total	Common Stock	Additional Paid-in- Capital	Retained Earnings	Accumulated Other Comprehensive Earnings	Treasury Stock	Class B Common Shares Common Stock
Beginning Balance at Dec. 31, 2018	$ 359,147,000	$ 9,419,000	$ 297,919,000	$ 142,447,000	$ 12,793,000	$ (103,433,000)	$ 2,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	4,051,000	29,000	4,370,000			(348,000)
Non-qualified stock option expense	1,939,000		1,939,000
Restricted stock awards	4,226,000	140,000	4,632,000			(546,000)
Net loss	(53,327,000)			(53,327,000)
Foreign currency translation adjustments	(8,499,000)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	(8,499,000)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	(570,000)				(570,000)
Defined benefit plans:
Amortization of prior service costs and unrecognized losses and credits	(596,000)				(596,000)
Comprehensive Income (Loss)	(62,992,000)
Dividends	(1,645,000)
Purchases of capped calls	0
Ending Balance at Dec. 31, 2019	308,516,000	9,588,000	312,650,000	87,475,000	3,128,000	(104,327,000)	2,000
Defined benefit plans:
Convertible Debt Derivative Adjustments	(220,000)		(220,000)
Exchange of Convertible Notes	4,010,000		4,010,000
Payments of Ordinary Dividends, Common Stock	1,645,000
Stock-based compensation expense	2,190,000	91,000	3,222,000			(1,123,000)
Restricted stock awards	4,748,000	137,000	5,195,000			(584,000)
Net loss	(28,280,000)			(28,280,000)
Foreign currency translation adjustments	43,405,000
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	43,405,000
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	(722,000)				(722,000)
Amortization of prior service costs and unrecognized losses and credits	(375,000)				(375,000)
Comprehensive Income (Loss)	14,028,000
Dividends	(414,000)
Purchases of capped calls	0
Adoption of Credit Loss Standard	(243,000)
Ending Balance at Dec. 31, 2020	333,846,000	9,816,000	326,088,000	58,538,000	45,436,000	(106,034,000)	2,000
Defined benefit plans:
Exchange of Convertible Notes	5,021,000		5,021,000
Payments of Ordinary Dividends, Common Stock	414,000
Stock-based compensation expense	(1,795,000)	52,000	(1,179,000)			(668,000)
Restricted stock awards	4,364,000	109,000	5,341,000			(1,086,000)
Net loss	(45,563,000)			(45,563,000)
Foreign currency translation adjustments	(28,724,000)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	(28,724,000)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	703,000				703,000
Amortization of prior service costs and unrecognized losses and credits	(427,000)				(427,000)
Comprehensive Income (Loss)	(74,011,000)
Adoption of ASU 2020-06	(25,128,000)		(34,798,000)	9,670,000
Purchases of capped calls	(18,787,000)		(18,787,000)
Ending Balance at Dec. 31, 2021	218,489,000	$ 9,977,000	$ 276,665,000	$ 22,645,000	$ 16,988,000	$ (107,788,000)	$ 2,000
Defined benefit plans:
Payments of Ordinary Dividends, Common Stock	$ 0