Summary of Significant Accounting Policies - Summary of Reconciliation of Amounts in Previously Reported Consolidated Financial Statements - Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Accounts receivable	$ 119,332	$ 77,609	$ 44,423
Total current assets	133,930	107,062	250,415
Total assets	1,433,769	1,223,527	1,198,644
Accounts payable	116,735	76,174
Accrued liabilities	56,909	41,662	55,044
Total current liabilities	208,284	149,594	131,519
Total liabilities	746,283	651,173	642,037
Accumulated deficit	(1,377,319)	(1,396,145)	(1,404,670)
Total stockholders' equity	687,486	572,354	556,607	$ 633,374
Total liabilities and stockholders' equity	$ 1,433,769	$ 1,223,527	1,198,644
As Reported [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Accounts receivable			43,638
Total current assets			249,630
Total assets			1,197,859
Accrued liabilities			64,150
Total current liabilities			140,625
Total liabilities			651,143
Accumulated deficit			(1,414,561)
Total stockholders' equity			546,716
Total liabilities and stockholders' equity			1,197,859
Adjustment [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Accounts receivable			785
Total current assets			785
Total assets			785
Accrued liabilities			(9,106)
Total current liabilities			(9,106)
Total liabilities			(9,106)
Accumulated deficit			9,891
Total stockholders' equity			9,891
Total liabilities and stockholders' equity			$ 785