CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Treasury stock, at cost	Non-controlling interests
Balance (in shares) at Dec. 31, 2018		25,413
Balance at Dec. 31, 2018	$ 296,668	$ 25,413	$ 122,667	$ 590,655	$ (443,304)	$ 1,237
Increase (Decrease) in Equity
Net income (loss)	(2,744)			(3,184)		440
Distributions to non-controlling interest holders	(620)					(620)
Share-based compensation expense	2,621		2,621
Exercise of stock options and issuance of restricted share units and restricted shares	28			(1,549)	1,577
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances	(585)			(1,163)	578
Balance (in shares) at Mar. 31, 2019		25,413
Balance at Mar. 31, 2019	295,368	$ 25,413	125,288	584,759	(441,149)	1,057
Balance (in shares) at Dec. 31, 2018		25,413
Balance at Dec. 31, 2018	296,668	$ 25,413	122,667	590,655	(443,304)	1,237
Increase (Decrease) in Equity
Net income (loss)	228
Balance (in shares) at Sep. 30, 2019		25,413
Balance at Sep. 30, 2019	288,656	$ 25,413	130,951	579,557	(448,590)	1,325
Balance (in shares) at Mar. 31, 2019		25,413
Balance at Mar. 31, 2019	295,368	$ 25,413	125,288	584,759	(441,149)	1,057
Increase (Decrease) in Equity
Net income (loss)	(4,604)			(5,844)		1,240
Distributions to non-controlling interest holders	(518)					(518)
Share-based compensation expense	2,832		2,832
Exercise of stock options and issuance of restricted share units and restricted shares	207			(3,473)	3,680
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances	(713)			(1,402)	689
Repurchase of shares	(6,700)				(6,700)
Balance (in shares) at Jun. 30, 2019		25,413
Balance at Jun. 30, 2019	285,872	$ 25,413	128,120	574,040	(443,480)	1,779
Increase (Decrease) in Equity
Net income (loss)	7,576			7,165		411
Distributions to non-controlling interest holders	(865)					(865)
Share-based compensation expense	2,831		2,831
Exercise of stock options and issuance of restricted share units and restricted shares	157			(1,214)	1,371
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances	(218)			(434)	216
Repurchase of shares	(6,697)				(6,697)
Balance (in shares) at Sep. 30, 2019		25,413
Balance at Sep. 30, 2019	288,656	$ 25,413	130,951	579,557	(448,590)	1,325
Balance (in shares) at Dec. 31, 2019		25,413
Balance at Dec. 31, 2019	(21,357)	$ 25,413	133,669	272,026	(453,934)	1,469
Increase (Decrease) in Equity
Net income (loss)	(11,545)			(11,650)		105
Distributions to non-controlling interest holders	(311)					(311)
Share-based compensation expense	2,894		2,894
Exercise of stock options and issuance of restricted share units and restricted shares	0			(4,796)	4,796
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances	(1,205)			(3,114)	1,909
Balance (in shares) at Mar. 31, 2020		25,413
Balance at Mar. 31, 2020	(31,524)	$ 25,413	136,563	252,466	(447,229)	1,263
Balance (in shares) at Dec. 31, 2019		25,413
Balance at Dec. 31, 2019	(21,357)	$ 25,413	133,669	272,026	(453,934)	1,469
Increase (Decrease) in Equity
Net income (loss)	(59,306)
Balance (in shares) at Sep. 30, 2020		25,413
Balance at Sep. 30, 2020	(76,578)	$ 25,413	140,225	198,756	(442,107)	1,135
Balance (in shares) at Mar. 31, 2020		25,413
Balance at Mar. 31, 2020	(31,524)	$ 25,413	136,563	252,466	(447,229)	1,263
Increase (Decrease) in Equity
Net income (loss)	(34,864)			(35,061)		197
Distributions to non-controlling interest holders	(180)					(180)
Share-based compensation expense	1,930		1,930
Exercise of stock options and issuance of restricted share units and restricted shares	0			(3,177)	3,177
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances	(212)			(1,205)	993
Balance (in shares) at Jun. 30, 2020		25,413
Balance at Jun. 30, 2020	(64,850)	$ 25,413	138,493	213,023	(443,059)	1,280
Increase (Decrease) in Equity
Net income (loss)	(12,897)			(13,237)		340
Distributions to non-controlling interest holders	(485)					(485)
Share-based compensation expense	1,732		1,732
Exercise of stock options and issuance of restricted share units and restricted shares	0			(747)	747
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances	(78)			(283)	205
Balance (in shares) at Sep. 30, 2020		25,413
Balance at Sep. 30, 2020	$ (76,578)	$ 25,413	$ 140,225	$ 198,756	$ (442,107)	$ 1,135