XML 98 R58.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Taxes - Additional Information (Detail) - USD ($)
 1 Months Ended 12 Months Ended
Sep. 30, 2015
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Taxes [Line Items]          
Federal statutory income tax rate     34.00%    
Claim settlement received $ 14,500,000       $ 14,452,000
Settlement recognized as additional paid-in capital, net of tax         9,495,000
Income tax benefit, claims settlement         5,000,000
Increase (decrease) in deferred tax assets valuation allowance     $ (28,900,000) $ 23,800,000 $ 5,000,000
Deferred tax assets, net operating loss carryforwards for federal     475,000,000    
Deferred tax assets, net operating loss carryforwards for state     142,000,000    
Federal research tax credit carryforwards     10,800,000    
State research tax credit carryforwards     $ 11,800,000    
Tax credit carryforward, expiration year     2018    
Federal tax rate reduction net of valuation allowance     $ 0    
Accrued interest and/or penalties     $ 0    
Maximum [Member]          
Income Taxes [Line Items]          
Federal statutory income tax rate     35.00%    
Scenario Plan [Member]          
Income Taxes [Line Items]          
Federal statutory income tax rate   21.00%      
State [Member]          
Income Taxes [Line Items]          
Operating loss carryforwards, expiration year     2018    
Federal [Member]          
Income Taxes [Line Items]          
Operating loss carryforwards, expiration year     2017