Summary of Significant Accounting Policies - Summary of Reconciliation of Amounts in Previously Reported Consolidated Financial Statements - Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Net loss	$ 36,490	$ 3,998	$ (19,036)	$ (2,626)	$ (13,122)	$ (16,694)	$ 11,494	$ 26,847	$ 18,826	$ 8,525	$ (206,735)
Deferred income taxes											540
Accounts receivable									(42,879)	(31,780)	(21,277)
Accounts payable and accrued liabilities									$ 84,231	$ 18,404	794
As Reported [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Net loss											(203,806)
Accounts receivable											(20,563)
Accounts payable and accrued liabilities											(2,849)
Adjustment [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Net loss											(2,929)
Accounts receivable											(714)
Accounts payable and accrued liabilities											$ 3,643