Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

v3.10.0.1
Fair Value Measurements (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
May 25, 2018
Dec. 31, 2017
Dec. 15, 2014
Level 1 | Recurring Basis        
Assets        
Total Assets $ 106,038   $ 39,400  
Liabilities        
Total liabilities 5,852   4,364  
Level 1 | Recurring Basis | Deferred compensation liability        
Liabilities        
Total liabilities 5,852   4,364  
Level 1 | Recurring Basis | Money market funds and other        
Assets        
Total Assets 106,038   39,400  
Level 3 | Recurring Basis        
Assets        
Total Assets 6,729   5,185  
Liabilities        
Total liabilities 707   2,781  
Level 3 | Recurring Basis | Contingent consideration        
Liabilities        
Total liabilities 707   2,781  
Level 3 | Recurring Basis | Asset to fund deferred compensation liability        
Assets        
Total Assets 6,729   5,185  
Fair Value | Recurring Basis        
Assets        
Total Assets 112,767   44,585  
Liabilities        
Total liabilities 6,559   7,145  
Fair Value | Recurring Basis | Contingent consideration        
Liabilities        
Total liabilities 707   2,781  
Fair Value | Recurring Basis | Deferred compensation liability        
Liabilities        
Total liabilities 5,852   4,364  
Fair Value | Recurring Basis | Money market funds and other        
Assets        
Total Assets 106,038   39,400  
Fair Value | Recurring Basis | Asset to fund deferred compensation liability        
Assets        
Total Assets 6,729   5,185  
Convertible Notes due 2019        
Fair Value Measurements        
Face amount 172,500   172,500 $ 172,500
Convertible Debt, Noncurrent 162,299   158,990  
2019 Convertible Notes        
Liabilities        
Total liabilities 182,333   180,180  
2019 Convertible Notes | Carrying Value        
Fair Value Measurements        
Convertible Debt, Noncurrent 162,299   158,990  
2023 Convertible Notes        
Fair Value Measurements        
Face amount   $ 345,000    
2023 Convertible Notes | Carrying Value        
Fair Value Measurements        
Convertible Debt, Noncurrent 289,562      
Liabilities        
Total liabilities 356,923      
Revolving credit facility        
Liabilities        
Total liabilities $ 0   $ 81,168