Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail)

v3.6.0.2
Income Taxes - Additional Information (Detail) - USD ($)
1 Months Ended 12 Months Ended
Sep. 30, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
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 in deferred tax assets valuation allowance   $ 23,800,000 $ 5,000,000 $ 9,800,000
Deferred tax assets, net operating loss carryforwards for federal   412,000,000    
Deferred tax assets, net operating loss carryforwards for state   177,000,000    
Federal research tax credit carryforwards   9,700,000    
State research tax credit carryforwards   $ 10,500,000    
Tax credit carryforward, expiration year   2018    
Accrued interest and/or penalties   $ 0    
State        
Income Taxes [Line Items]        
Operating loss carryforwards, expiration year   2018    
Federal        
Income Taxes [Line Items]        
Operating loss carryforwards, expiration year   2018