Guarantor Subsidiaries - Schedule of Condensed Consolidating Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net Income (Loss)	$ 121,220	$ (138,225)	$ (170,378)
Other comprehensive income (loss)	0	0	0
Comprehensive Income (Loss)	121,220	(138,225)	(170,378)
Reportable Legal Entities [Member] \| Parent Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net Income (Loss)		(138,225)	(170,378)
Other comprehensive income (loss)		0	0
Comprehensive Income (Loss)		(138,225)	(170,378)
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net Income (Loss)		(838)	(87)
Other comprehensive income (loss)		0	0
Comprehensive Income (Loss)		(838)	(87)
Reportable Legal Entities [Member] \| Parent Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net Income (Loss)	121,220
Other comprehensive income (loss)	0
Comprehensive Income (Loss)	121,220
Reportable Legal Entities [Member] \| Subsidiary Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net Income (Loss)	121,220
Other comprehensive income (loss)	0
Comprehensive Income (Loss)	121,220
Intercompany Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net Income (Loss)	(121,220)	838	87
Other comprehensive income (loss)	0	0	0
Comprehensive Income (Loss)	$ (121,220)	$ 838	$ 87

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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