CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common stock	Additional paid-in capital	Additional paid-in capital Cumulative Effect, Period of Adoption, Adjustment	Retained earnings	Retained earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive income (loss)	Accumulated other comprehensive income (loss) Cumulative Effect, Period of Adoption, Adjustment	Treasury stock, at cost	Non-controlling interests
Balance at Dec. 31, 2017	$ 339,985	$ (10,448)	$ 25,413	$ 112,475	$ 0	$ 626,600	$ (9,715)	$ 733	$ (733)	$ (426,609)	$ 1,373
Balance (in shares) at Dec. 31, 2017			25,413
Increase (Decrease) in Equity
Net loss	(2,699)					(5,382)					2,683
Distributions to non-controlling interest holders	(2,819)										(2,819)
Share-based compensation expense	$ 10,192			10,192
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201409Member
Exercise of stock options and issuance of restricted shares	$ 3,644					(19,245)				22,889
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances and stock option exercises	(825)					(1,603)				778
Repurchase of shares	(40,362)									(40,362)
Balance at Dec. 31, 2018	296,668		$ 25,413	122,667		590,655		0		(443,304)	1,237
Balance (in shares) at Dec. 31, 2018			25,413
Increase (Decrease) in Equity
Net loss	(305,857)					(307,969)					2,112
Distributions to non-controlling interest holders	(2,752)										(2,752)
Share-based compensation expense	11,874			11,002							872
Exercise of stock options and issuance of restricted shares	400					(7,222)				7,622
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances and stock option exercises	(1,695)					(3,438)				1,743
Repurchase of shares	(19,995)									(19,995)
Balance at Dec. 31, 2019	(21,357)		$ 25,413	133,669		272,026		0		(453,934)	1,469
Balance (in shares) at Dec. 31, 2019			25,413
Increase (Decrease) in Equity
Net loss	(66,315)					(67,156)					841
Distributions to non-controlling interest holders	(1,101)										(1,101)
Share-based compensation expense	7,804			7,804
Exercise of stock options and issuance of restricted shares	0					(9,548)				9,548
Treasury shares withheld for the payment of tax on restricted share unit and restricted share issuances and stock option exercises	(1,587)					(4,939)				3,352
Balance at Dec. 31, 2020	$ (82,556)		$ 25,413	$ 141,473		$ 190,383		$ 0		$ (441,034)	$ 1,209
Balance (in shares) at Dec. 31, 2020			25,413