Condensed Consolidating Guarantor Financial Information Condensed Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Statement of Comprehensive Income Captions [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 27,421	$ (63,846)	$ 66,821
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment	(1,568)	14,321	(3,174)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	25,853	(49,525)	63,647
Consolidation, Eliminations [Member]
Condensed Statement of Comprehensive Income Captions [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(63,489)	14,989	(107,126)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(63,489)	14,989	(107,126)
Parent Company [Member]
Condensed Statement of Comprehensive Income Captions [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	27,421	(63,846)	67,149
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	27,421	(63,846)	67,149
Guarantor Subsidiaries [Member]
Condensed Statement of Comprehensive Income Captions [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	74,139	(4,680)	101,907
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment	(149)	31	(81)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	73,990	(4,649)	101,826
Non-Guarantor Subsidiaries [Member]
Condensed Statement of Comprehensive Income Captions [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(10,650)	(10,309)	4,891
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment	(1,419)	14,290	(3,093)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ (12,069)	$ 3,981	$ 1,798