XML 174 R78.htm IDEA: XBRL DOCUMENT v3.10.0.1
Income Taxes - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Reconciliation Of Income Taxes [Line Items]      
Federal statutory income tax rate 21.00% 35.00% 35.00%
Increase in valuation allowance $ 36,100,000 $ 5,500,000 $ 16,500,000
Valuation allowance changes, description The Company does not expect any significant changes in its valuation allowance positions within the next 12 months.    
Federal net operating loss carryforwards $ 479,500,000    
State net operating loss carryforwards 301,400,000    
Research and development credits $ 11,154,000 $ 9,402,000  
Minimum percentage chances of tax benefit to be realized on examination 50.00%    
Unrecognized tax benefits affect the Company's effective tax rate $ 0    
Interest or penalties recorded $ 0    
Expected significant change in unrecognized tax benefits, description The Company does not expect any significant change in its unrecognized tax benefits within the next 12 months    
Federal [Member]      
Reconciliation Of Income Taxes [Line Items]      
Net operating loss, carryforwards, period 20 years    
Net operating loss carryforwards, expiration year Dec. 31, 2037    
Interest expense carryforward $ 10,000,000    
Research and development credits $ 6,800,000    
Research and development credit carryforwards, expiration year Dec. 31, 2038    
State [Member]      
Reconciliation Of Income Taxes [Line Items]      
Net operating loss carryforwards, expiration year Dec. 31, 2038    
Research and development credits $ 3,500,000    
Research and development credit carryforwards, expiration year Dec. 31, 2033    
Investments credits $ 932,000    
Ireland [Member] | Earliest Tax Year [Member]      
Reconciliation Of Income Taxes [Line Items]      
Open tax year 2014    
Ireland [Member] | Latest Tax Year [Member]      
Reconciliation Of Income Taxes [Line Items]      
Open tax year 2018