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, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Net loss	$ (13,122)	$ (16,694)	$ 11,494	$ 26,847	$ (62,089)	$ (25,949)	$ (73,163)	$ (45,534)	$ 8,525	$ (206,735)	$ (961,791)
Deferred income taxes										540	(74,481)
Accounts receivable									(31,780)	(21,277)	20,209
Accounts payable and accrued liabilities									$ 18,404	794	17,050
As Reported [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Net loss										(203,806)	(971,410)
Deferred income taxes											(72,761)
Accounts receivable										(20,563)	20,437
Accounts payable and accrued liabilities										(2,849)	24,721
Adjustment [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Net loss										(2,929)	9,619
Deferred income taxes											(1,720)
Accounts receivable										(714)	(228)
Accounts payable and accrued liabilities										$ 3,643	$ (7,671)