Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Narrative (Details)

v3.19.3
Fair Value Measurements - Narrative (Details) - USD ($)
Sep. 30, 2019
Dec. 31, 2018
May 25, 2018
Dec. 15, 2014
Fair Value Measurements        
Convertible Notes due 2023 $ 302,785,000 $ 294,725,000    
Revolving credit facility balance 100,000,000 0    
2019 Convertible Notes        
Fair Value Measurements        
Face amount       $ 172,500,000
Debt instrument, fair value disclosure 174,656,000 174,101,000    
2019 Convertible Notes | Carrying Value        
Fair Value Measurements        
Convertible Notes due 2023 170,966,000 165,711,000    
2023 Convertible Notes        
Fair Value Measurements        
Face amount     $ 345,000,000  
Debt instrument, fair value disclosure 370,923,000 339,024,000    
2023 Convertible Notes | Carrying Value        
Fair Value Measurements        
Convertible Notes due 2023 302,785,000 294,725,000    
Second Amended and Restated Credit Agreement        
Fair Value Measurements        
Revolving credit facility balance $ 100,000,000 $ 0