XML 83 R69.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Taxes - Narrative (Details) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Operating Loss Carryforwards [Line Items]        
Income tax benefit   $ 0 $ 0 $ 2,097,766
Excess tax benefits on stock compensation $ 1,100,000      
Tax benefits expired   13,400,000    
Decrease in deferred tax assets   50,000,000    
Decrease in valuation allowance   50,200,000    
Provisional income tax benefit   (200,000)    
Unrecognized tax benefits that would impact effective tax rate   7,100,000    
Federal        
Operating Loss Carryforwards [Line Items]        
Net operating loss carryforwards that will expire due to IRC Section 382 limitations   298,900,000    
California        
Operating Loss Carryforwards [Line Items]        
Net operating loss carryforwards that will expire due to IRC Section 382 limitations   68,600,000    
Pennsylvania        
Operating Loss Carryforwards [Line Items]        
Net operating loss carryforwards that will expire due to IRC Section 382 limitations   75,600,000    
Research Tax Credit Carryforward | Federal        
Operating Loss Carryforwards [Line Items]        
Tax credit carryforward amount   11,100,000    
Research Tax Credit Carryforward | State        
Operating Loss Carryforwards [Line Items]        
Tax credit carryforward amount   $ 2,100,000