Unaudited Condensed Consolidated Statements of Stockholders' (Deficit) Equity - 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, 2016										$ (70,428)
Ending Balance at Mar. 31, 2017										(68,369)
Beginning Balance at Dec. 31, 2017	$ (50,976)			$ 90		$ 1,044,518			$ (223,718)	(51,280)	$ (844,030)	$ 23,444
Beginning Balance (in shares) at Dec. 31, 2017				90,159
Shares issued on vesting of restricted stock	1			$ 1
Shares issued on vesting of restricted stock (in shares)				245
Shares issued on conversion of 5.75% Convertible Notes	8,746	$ 8,746			$ 6		$ 8,740
Shares issued on conversion of 5.75% Convertible Notes (in shares)					6,412
Writeoff of equity component of 1.50% Convertible Notes			$ (23,250)					$ (23,250)
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)			$ 97		$ 1,031,084			(182,105)	(45,342)	$ (844,055)	25,495
Ending Balance (in shares) at Mar. 31, 2018				96,816
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