CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock, at cost	Non-controlling interests
Balance (in shares) at Dec. 31, 2016		25,413
Balance at Dec. 31, 2016	$ 62,194	$ 25,413	$ 107,288	$ 333,786	$ (1,745)	$ (403,953)	$ 1,405
Increase (Decrease) in Equity
Net income	24,648			22,541			2,107
Other comprehensive income, net of tax	212				212
Distributions to non-controlling interest holders	(2,143)						(2,143)
Share-based compensation expense	3,237		3,237
Exercise of stock options and issuance of restricted shares	2,084			(11,787)		13,871
Treasury shares withheld for the payment of tax on restricted share issuances and stock option exercises	(1,088)			(1,497)		409
Repurchase of shares	(24,995)					(24,995)
Balance (in shares) at Sep. 30, 2017		25,413
Balance at Sep. 30, 2017	64,149	$ 25,413	111,457	342,111	(1,533)	(414,668)	1,369
Balance (in shares) at Dec. 31, 2017		25,413
Balance at Dec. 31, 2017	339,985	$ 25,413	112,475	626,600	733	(426,609)	1,373
Increase (Decrease) in Equity
Net income	8,169			6,103			2,066
Distributions to non-controlling interest holders	(1,912)						(1,912)
Share-based compensation expense	6,150		6,150
Exercise of stock options and issuance of restricted shares	3,576			(18,524)		22,100
Treasury shares withheld for the payment of tax on restricted share issuances and stock option exercises	(608)			(1,121)		513
Repurchase of shares	(21,771)					(21,771)
Balance (in shares) at Sep. 30, 2018		25,413
Balance at Sep. 30, 2018	$ 323,141	$ 25,413	$ 118,625	$ 603,343	$ 0	$ (425,767)	$ 1,527