CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interest [Member]	Total
Beginning balance at Dec. 31, 2017	$ 512	$ 896,759	$ (13,253)	$ (479,170)	$ (26,692)		$ 378,156
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income				27,339			27,339
Other comprehensive income, net of income taxes					78		78
Payment of dividend		167	(454)	(43,461)			(43,748)
Restricted stock units and stock options surrendered	1	(3,692)					(3,691)
Stock-based compensation expense		1,923					1,923
Ending balance at Mar. 31, 2018	513	895,157	(13,707)	(495,426)	(26,614)		359,923
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Transition adjustment related to adoption of ASU | ASU 2014-09 [Member]				(134)			(134)
Beginning balance at Dec. 31, 2018	513	900,795	(15,183)	(388,524)	(28,024)		469,577
Beginning balance at Dec. 31, 2018						$ 287,433	287,433
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income				29,408		(6,738)	29,408
Adjustment of noncontrolling interest to redemption value				(10,420)		10,420	(10,420)
Other comprehensive income, net of income taxes					109		109
Payment of dividend		168	(504)	(46,076)			(46,412)
Restricted stock units and stock options surrendered	1	(3,825)					(3,824)
Stock-based compensation expense		2,026					2,026
Ending balance at Mar. 31, 2019	$ 514	$ 899,164	$ (15,687)	(412,905)	(30,622)		440,464
Ending balance at Mar. 31, 2019						$ 291,115	$ 291,115
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Transition adjustment related to adoption of ASU				$ 2,707	$ (2,707)