Annual report pursuant to Section 13 and 15(d)

Restructuring Charges - Additional Information (Details)

v3.6.0.2
Restructuring Charges - Additional Information (Details)
 6 Months Ended 12 Months Ended
Dec. 19, 2016
Employee
Jan. 05, 2012
Position
Dec. 31, 2015
Employee
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Dec. 31, 2017
USD ($)
Restructuring Cost And Reserve [Line Items]              
Restructuring charges (credit)       $ 4,566,000 $ 3,699,000 $ 84,000  
Non-cash charges       817,000      
Impairment of property and equipment       198,000 0 0  
Leasehold Improvements [Member]              
Restructuring Cost And Reserve [Line Items]              
Impairment of property and equipment       200,000 0 0  
Stock-based Compensation [Member]              
Restructuring Cost And Reserve [Line Items]              
Non-cash charges       619,000      
2016 Restructuring [Member]              
Restructuring Cost And Reserve [Line Items]              
Number of employees terminated | Employee 57            
Total expenses recognized       3,800,000      
Payments for restructuring expenses       200,000      
2016 Restructuring [Member] | Forecast [Member]              
Restructuring Cost And Reserve [Line Items]              
Expected remaining future payments for restructuring             $ 3,600,000
2016 Restructuring [Member] | Leasehold Improvements [Member]              
Restructuring Cost And Reserve [Line Items]              
Impairment of property and equipment       200,000      
2016 Restructuring [Member] | Severance, Other Termination Benefits and Outplacement Services [Member]              
Restructuring Cost And Reserve [Line Items]              
Restructuring charges (credit)       3,800,000      
2016 Restructuring [Member] | Stock-based Compensation [Member]              
Restructuring Cost And Reserve [Line Items]              
Non-cash charges       600,000      
2015 Restructuring [Member]              
Restructuring Cost And Reserve [Line Items]              
Number of employees terminated | Employee     52        
2015 Restructuring [Member] | Severance, Other Termination Benefits and Outplacement Services [Member]              
Restructuring Cost And Reserve [Line Items]              
Restructuring charges (credit)       (32,000) 2,900,000    
2015 Restructuring [Member] | Contract Termination Costs [Member]              
Restructuring Cost And Reserve [Line Items]              
Restructuring charges (credit)       29,000 800,000    
2012 Restructuring [Member]              
Restructuring Cost And Reserve [Line Items]              
Number of positions eliminated | Position   84          
Number of positions eliminated (in hundredths)   34.00%          
2012 Restructuring [Member] | Facility Costs [Member]              
Restructuring Cost And Reserve [Line Items]              
Restructuring charges (credit)       $ 0 $ 0 $ 100,000