Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Details)

v3.8.0.1
Stock-Based Compensation (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Stock Based Compensation      
Allocated Share-based Compensation Expense $ 1,405 $ 1,448  
Fair value assumptions      
Dividend rate 0.00%    
Options      
Unrecognized compensation cost options $ 9,000    
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 1 year 6 months    
Common Stock, Capital Shares Reserved for Future Issuance 2,800,000    
2014 Plan | Awards | Series A common stock      
Options      
Outstanding beginning balance (in shares) 404,000    
Exercised (in shares) (5,000)    
Outstanding ending balance (in shares) 399,000    
Number of awards exercisable (in shares) 397,000    
WAEP Outstanding beginning balance (in dollars per share) $ 33.16    
WAEP options exercised (in dollars per share) 27.88    
WAEP Outstanding ending balance (in dollars per share) 33.24    
WAEP options exercisable (in dollars per share) $ 33.19    
Weighted average remaining contractual life outstanding 1 year 8 months 12 days    
Weighted average remaining contractual life exercisable 1 year 8 months 12 days    
Aggregate intrinsic value outstanding $ 21,000    
Aggregate intrinsic value exercisable $ 20,000    
2014 Plan | Awards | Series C common stock      
Options      
Outstanding beginning balance (in shares) 2,388,000    
Exercised (in shares) (24,000)    
Outstanding ending balance (in shares) 2,364,000    
Number of awards exercisable (in shares) 844,000    
WAEP Outstanding beginning balance (in dollars per share) $ 43.35    
WAEP options exercised (in dollars per share) 28.57    
WAEP Outstanding ending balance (in dollars per share) 43.50    
WAEP options exercisable (in dollars per share) $ 34.54    
Weighted average remaining contractual life outstanding 5 years    
Weighted average remaining contractual life exercisable 1 year 10 months 24 days    
Aggregate intrinsic value outstanding $ 100,000    
Aggregate intrinsic value exercisable $ 43,000    
2014 Plan | Options      
Options      
Options granted (in shares) 0    
Operating expense      
Stock Based Compensation      
Allocated Share-based Compensation Expense   1  
Selling, general and administrative      
Stock Based Compensation      
Allocated Share-based Compensation Expense $ 1,388 1,220  
Research and development      
Stock Based Compensation      
Allocated Share-based Compensation Expense 17 $ 227  
Other liabilities | Skyhook | LTIPs | PARs and PSUs | Significant other observable inputs (Level 2)      
Options      
Deferred compensation $ 1,200   $ 1,200