Unaudited Condensed Consolidated Statements of Stockholders' Deficit - USD ($) shares in Thousands, $ in Thousands	Total	5.75% Convertible Notes	1.50% Convertible Notes	Common Stock	Common Stock 5.75% Convertible Notes	Additional Paid-in Capital	Additional Paid-in Capital 5.75% Convertible Notes	Additional Paid-in Capital 1.50% Convertible Notes	Accumulated Losses	AOCI Attributable to Parent	Treasury Stock	Noncontrolling Interest
Beginning Balance at Dec. 31, 2017	$ (50,976)			$ 9		$ 1,044,599			$ (223,718)	$ (51,280)	$ (844,030)	$ 23,444
Beginning Balance (in shares) at Dec. 31, 2017				9,016
Shares issued on vesting of restricted stock (in shares)				25
Shares issued on conversion of 5.75% Convertible Notes	8,747	$ 8,747			$ 1		$ 8,746
Shares issued on conversion of 5.75% Convertible Notes (in shares)					641
Write-off of equity component of 1.50% Convertible Notes			$ (23,250)					$ (23,250)
Cumulative effect of accounting change for adoption | ASC 606	17,716								16,540			1,176
Cumulative effect of accounting change for adoption | ASU 2016-01									(3,177)	3,177
Shares repurchased on vesting of restricted stock and exercise of stock options	(25)										(25)
Compensation expense in connection with restricted stock and stock options	1,019					1,019
Payments from non-controlling interest holders, net of imputed interest	195											195
Change in redemption value of redeemable non-controlling interest	494								494
Net income	30,613								27,756			2,857
Tax benefit related to amortization of convertible notes' discount	35					35
Foreign currency translation	2,783					22				2,761
Distributions to joint ventures	(2,177)											(2,177)
Ending Balance at Mar. 31, 2018	(14,826)			$ 10		1,031,171			(182,105)	(45,342)	(844,055)	25,495
Ending Balance (in shares) at Mar. 31, 2018				9,682
Beginning Balance at Dec. 31, 2018	(145,735)			$ 11		1,037,372			(312,796)	(53,068)	(844,253)	26,999
Beginning Balance (in shares) at Dec. 31, 2018				11,162
Shares issued on vesting of restricted stock	0			$ 0
Shares issued on vesting of restricted stock (in shares)				87
Shares issued on conversion of 5.75% Convertible Notes	2,001	$ 2,001			$ 1		$ 2,000
Shares issued on conversion of 5.75% Convertible Notes (in shares)					958
Shares repurchased on vesting of restricted stock and exercise of stock options	(56)										(56)
Compensation expense in connection with restricted stock and stock options	140					140
Change in redemption value of redeemable non-controlling interest	391								391
Reclass from redeemable NCI	3,903											3,903
Net income	21,306								17,945			3,361
Foreign currency translation	(1,762)					(38)				(1,724)
Distributions to joint ventures	(2,649)											(2,649)
Ending Balance at Mar. 31, 2019	$ (122,461)			$ 12		$ 1,039,474			$ (294,460)	$ (54,792)	$ (844,309)	$ 31,614
Ending Balance (in shares) at Mar. 31, 2019				12,207