Annual report pursuant to Section 13 and 15(d)

Reconciliation of Tax Computed at Statutory Federal Rate to Income Tax Expense in Statements of Operations (Detail)

v3.8.0.1
Reconciliation of Tax Computed at Statutory Federal Rate to Income Tax Expense in Statements of Operations (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Schedule of Effective Tax Rate Reconciliation [Line Items]      
Tax benefit at statutory federal rate $ (18,100) $ (300) $ (800)
Change in valuation allowance 7,500 1,500 400
Change in income tax rate to 21% 8,800    
Non-deductible expenses 2,300 500 1,100
Adjustment to net operating loss carryforwards     (500)
Other adjustments (500) (1,700) (200)
Income tax benefit $ 0 $ 0 $ 0
Tax benefit at statutory federal rate (34.00%) (34.00%) (34.00%)
Change in valuation allowance 14.10% 178.80% 16.20%
Change in income tax rate to 21% 16.60%    
Non-deductible expenses 4.30% 57.00% 45.00%
Adjustment to net operating loss carryforwards     (21.10%)
Other adjustments (0.20%) (201.80%) (6.10%)
Income tax benefit 0.80%