Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Shares	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Shares	Non-Controlling Interest	Common Stock Outstanding
Balance at Beginning of Period at Dec. 31, 2017	$ 148,732	$ 1,148	$ 54,463	$ 173,855	$ (8,353)	$ (76,269)	$ 3,888
Balance at Beginning of Period (shares) at Dec. 31, 2017		44,796,252				(612,047)		44,184,205
Stock-based compensation	34,194		2,975			$ 31,219
Stock-based compensation (shares)						218,625		218,625
Repurchase of common shares	(7,451)					$ (7,451)
Repurchase of common shares (shares)						(85,985)		(85,985)
Dividends paid	(97,251)			(97,251)
Non-controlling interest additions	(10)						(10)
Pension and other post retirement benefit plans, net of income tax	2,512				2,512
Interest rate swaps, net of income tax	385				385
Net income (loss)	79,789			79,526			263
Balance at End of Period at Dec. 31, 2018	$ 160,900	$ 1,148	57,438	156,130	(5,456)	$ (52,501)	4,141
Balance at End of Period (shares) at Dec. 31, 2018		44,796,252				(479,407)		44,316,845
Cash Dividends per Share	$ 2.20
Stock-based compensation	$ 20,879		(5,566)			$ 26,445
Stock-based compensation (shares)						220,417		220,417
Repurchase of common shares	(3,308)					$ (3,308)
Repurchase of common shares (shares)						(71,700)		(71,700)
Dividends paid	(97,574)			(97,574)
Pension and other post retirement benefit plans, net of income tax	10				10
Interest rate swaps, net of income tax	(884)				(884)
Net income (loss)	102,117			101,983			134
Balance at End of Period at Dec. 31, 2019	$ 182,140	$ 1,148	51,872	160,539	(6,330)	$ (29,364)	4,275
Balance at End of Period (shares) at Dec. 31, 2019		44,796,252				(330,690)		44,465,562
Cash Dividends per Share	$ 2.20
Stock-based compensation	$ 7,394		(10,688)			$ 18,082
Stock-based compensation (shares)	208,168					208,168		208,168
Repurchase of common shares	$ (2,793)					$ (2,793)
Repurchase of common shares (shares)						(100,929)		(100,929)
Dividends paid	(12,446)			(12,446)
Non-controlling interest dividends	(355)						(355)
Pension and other post retirement benefit plans, net of income tax	265				265
Interest rate swaps, net of income tax	(1,135)				(1,135)
Net income (loss)	(97,497)			(97,637)			140
Balance at End of Period at Dec. 31, 2020	$ 75,573	$ 1,148	$ 41,184	$ 50,456	$ (7,200)	$ (14,075)	$ 4,060
Balance at End of Period (shares) at Dec. 31, 2020		44,796,252				(223,451)		44,572,801
Cash Dividends per Share	$ 0.28