CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Treasury stock [Member]	Treasury stock reserved for contractual obligations	Accumulated other comprehensive income (loss) [Member]	Parent [Member]	Noncontrolling interest [Member]
Balance, Beginning at Dec. 31, 2016	$ 292,879	$ 0	$ 479,075	$ 17,214	$ (10,119)	$ (1,075)	$ (188,278)	$ 296,817	$ (3,938)
Balance, Beginning (in shares) at Dec. 31, 2016		54,169,880
Change During Period Common Stock Shares Held In Employee Trust	(2,018)		0			0		0	(2,018)
Net income (loss)	(64,079)			(60,042)				(60,042)	(4,121)
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	(64,163)
CTA, net of tax	30,818						29,679	29,679	(768)
Temporary Equity, Foreign Currency Translation Adjustments	28,911
Pension liability adjustments, net of tax	1,523						1,523	1,523
Dividends declared	(1,194)			(1,194)				(1,194)
Note conversion, Shares		5,462,264
Note conversion	58,460		58,460					58,460
Redemption value adjustment	(6,393)		(6,393)					(6,393)
Stock Issued During Period, Shares, Restricted Stock Award, Gross		119,173
Stock-based compensation	1,539		468		1,071			1,539
Issuance of treasury stock under 401(k) plan	540		98		442			540
Issuance of treasury stock under 401(k) plan (in shares)		49,242
Balance, Ending at Dec. 31, 2017	310,084		531,708	(44,022)	(8,606)	(1,075)	(157,076)	320,929	(10,845)
Balance, Ending (in shares) at Dec. 31, 2017		59,800,559
Loss attributable to redeemable noncontrolling interest	84
Currency translation	1,907
Stock Issued During Period, Value, Acquisitions	(149)		1,032				4,325	5,357	(5,208)
Change During Period Common Stock Shares Held In Employee Trust	(1,188)		(113)					(1,188)
Net income (loss)	13,045			16,087				16,087	(1,951)
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	14,136
CTA, net of tax	(41,966)						(38,520)	(38,520)	1,050
Temporary Equity, Foreign Currency Translation Adjustments	(37,470)
Pension liability adjustments, net of tax	(3,650)						(3,650)	(3,650)
Dividends declared	(1,201)			(1,201)				(1,201)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	123			88				88	35
Note conversion	$ 0
Restricted stock awards (in shares)	376,500
Redemption value adjustment	$ (12,207)		(12,207)					(12,207)
Stock Issued During Period, Shares, Restricted Stock Award, Gross		61,897
Stock-based compensation	1,130		844		286			1,130
Variable Interest Entity, Members Draw	(2,448)		0			0		0	(2,448)
Issuance of treasury stock under 401(k) plan	561		72		489			561
Issuance of treasury stock under 401(k) plan (in shares)		54,517
Balance, Ending at Dec. 31, 2018	270,097	$ 0	519,498	(29,048)	(7,831)	0	(203,571)	279,048	(8,951)
Balance, Ending (in shares) at Dec. 31, 2018		59,916,973
Loss attributable to redeemable noncontrolling interest	(1,091)
Currency translation	(4,496)
Change During Period Common Stock Shares Held In Employee Trust	2,008					(1,075)		0	(2,008)
Net income (loss)	(51,519)			(48,425)				(48,425)	(2,275)
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	(50,700)
CTA, net of tax	(8,949)						(10,510)	(10,510)	878
Temporary Equity, Foreign Currency Translation Adjustments	(9,632)
Pension liability adjustments, net of tax	6,566						6,566	6,566
Dividends declared	(1,207)			(1,207)				(1,207)
Note conversion, Shares		0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(587)		0	4,346			(4,933)	(587)
Note conversion	$ 0
Restricted stock awards (in shares)	355,201
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	$ 0		(6,203)				6,203	0
Noncontrolling Interest, Period Increase (Decrease)	$ 24,882		9,437					9,437	15,445
Exercise of stock options (in shares)	0
Redemption value adjustment	$ (1,928)		(1,928)					(1,928)
Stock-based compensation	1,381		213		1,168			1,381
Variable Interest Entity, Members Draw	(2,968)							0	(2,968)
Issuance of treasury stock under 401(k) plan	1,076		(1,353)		2,429			1,076
Issuance of treasury stock under 401(k) plan (in shares)		266,121
Balance, Ending at Dec. 31, 2019	238,988	$ 0	$ 532,070	$ (74,334)	$ (4,234)	$ 0	$ (218,651)	$ 234,851	$ 4,137
Balance, Ending (in shares) at Dec. 31, 2019		60,283,212
Loss attributable to redeemable noncontrolling interest	(819)
Currency translation	$ 683