Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

v3.10.0.1
Fair Value Measurements (Details) - USD ($)
$ in Thousands
Sep. 30, 2018
May 25, 2018
Dec. 31, 2017
Dec. 15, 2014
Level 1 | Recurring Basis        
Assets        
Total Assets $ 119,276   $ 39,400  
Liabilities        
Total liabilities 6,388   4,364  
Level 1 | Recurring Basis | Deferred compensation liability        
Liabilities        
Total liabilities 6,388   4,364  
Level 1 | Recurring Basis | Money market funds and other        
Assets        
Total Assets 119,276   39,400  
Level 3 | Recurring Basis        
Assets        
Total Assets 6,879   5,185  
Liabilities        
Total liabilities 719   2,781  
Level 3 | Recurring Basis | Contingent consideration        
Liabilities        
Total liabilities 719   2,781  
Level 3 | Recurring Basis | Asset to fund deferred compensation liability        
Assets        
Total Assets 6,879   5,185  
Convertible Notes due 2019        
Liabilities        
Face amount 172,500   172,500 $ 172,500
Convertible Debt, Noncurrent 0   158,990  
2019 Convertible Notes        
Liabilities        
Total liabilities 191,044   180,180  
2023 Convertible Notes        
Liabilities        
Face amount   $ 345,000    
Revolving credit facility        
Liabilities        
Total liabilities 0   81,168  
Carrying Value | 2019 Convertible Notes        
Liabilities        
Convertible Debt, Noncurrent 164,003   158,990  
Carrying Value | 2023 Convertible Notes        
Liabilities        
Total liabilities 373,423      
Convertible Debt, Noncurrent 292,078      
Fair Value | Recurring Basis        
Assets        
Total Assets 126,155   44,585  
Liabilities        
Total liabilities 7,107   7,145  
Fair Value | Recurring Basis | Contingent consideration        
Liabilities        
Total liabilities 719   2,781  
Fair Value | Recurring Basis | Deferred compensation liability        
Liabilities        
Total liabilities 6,388   4,364  
Fair Value | Recurring Basis | Money market funds and other        
Assets        
Total Assets 119,276   39,400  
Fair Value | Recurring Basis | Asset to fund deferred compensation liability        
Assets        
Total Assets $ 6,879   $ 5,185