XML 72 R58.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Transition tax on foreign subsidiaries   $ 0    
Amount of decrease in deferred tax assets   $ (19,800)    
Reconciliation of the U.S. statutory income tax rate to the effective income tax rate        
Federal income tax (benefit) at statutory rate   34.00% 34.00% 34.00%
Permanent differences   (1.16%) (0.85%) (0.86%)
Federal research and development credits and adjustments   2.36% 2.43% 2.64%
State income tax benefit, net of federal benefit   5.80% 5.70% 5.77%
Tax reform deferred rate change   (72.21)    
Other (as a percent)   (0.36%) (0.40%) 0.28%
Change in valuation allowance   31.57% (40.88%) (41.82%)
Deferred tax assets        
Net operating loss carryforwards   $ 41,436 $ 48,682  
Tax credit carryforwards   5,896 4,833  
Capitalized research and development   1,879 3,394  
Capitalized legal expenses   1,156 1,597  
Other differences   1,048 1,335  
Total deferred tax assets   51,415 59,841  
Valuation allowance   (51,415) (59,841)  
Valuation allowance        
Recorded increase (decrease) in valuation allowance   (8,400) $ 14,700 $ 13,600
Federal        
Valuation allowance        
Net operating loss carryforwards   152,100    
Tax credit carryforwards   4,500    
State        
Valuation allowance        
Net operating loss carryforwards   150,400    
Tax credit carryforwards   1,800    
Accounting Standards Update 2016-09        
Valuation allowance        
Recorded increase (decrease) in valuation allowance   $ 200    
Forecast        
Reconciliation of the U.S. statutory income tax rate to the effective income tax rate        
Federal income tax (benefit) at statutory rate 21.00%