Supplemental Guarantor Information (Consolidating Statements of Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net loss	$ (26,390)	$ (63,806)	$ (86,114)	$ (155,465)
Change in cumulative translation adjustment, net of tax	(7,053)	6,022	(2,665)	7,746
Comprehensive loss	(33,443)	(57,784)	(88,779)	(147,719)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net loss	15,229	88,499	92,591	234,780
Change in cumulative translation adjustment, net of tax	14,106	(12,044)	5,330	(15,492)
Comprehensive loss	29,335	76,455	97,921	219,288
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net loss	(26,390)	(63,806)	(86,114)	(155,465)
Change in cumulative translation adjustment, net of tax	(7,053)	6,022	(2,665)	7,746
Comprehensive loss	(33,443)	(57,784)	(88,779)	(147,719)
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net loss	(26,390)	(63,806)	(86,114)	(155,465)
Change in cumulative translation adjustment, net of tax	(7,053)	6,022	(2,665)	7,746
Comprehensive loss	(33,443)	(57,784)	(88,779)	(147,719)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net loss	16,429	(10,151)	11,245	(49,012)
Comprehensive loss	16,429	(10,151)	11,245	(49,012)
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net loss	(5,268)	(14,542)	(17,722)	(30,303)
Change in cumulative translation adjustment, net of tax	(7,053)	6,022	(2,665)	7,746
Comprehensive loss	$ (12,321)	$ (8,520)	$ (20,387)	$ (22,557)