Quarterly report pursuant to Section 13 or 15(d)

Debt - Convertible Notes (Details)

v3.19.3
Debt - Convertible Notes (Details)
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2019
USD ($)
$ / shares
Sep. 30, 2018
Sep. 30, 2019
USD ($)
$ / shares
Sep. 30, 2018
Dec. 31, 2014
USD ($)
$ / shares
Dec. 31, 2018
USD ($)
May 31, 2018
USD ($)
Convertible Notes due 2019              
Debt Instrument [Line Items]              
Face amount | $ $ 172,500,000   $ 172,500,000   $ 172,500,000 $ 172,500,000  
Interest rate (as a percent)         1.75%    
Conversion ratio         0.0159022    
Conversion price (in dollars per share) | $ / shares         $ 62.88    
Effective interest rate (as a percent) 6.00% 6.00% 6.00% 6.00%      
Convertible notes due 2023              
Debt Instrument [Line Items]              
Face amount | $             $ 345,000,000
Interest rate (as a percent)             1.75%
Conversion price (in dollars per share) | $ / shares $ 68.31   $ 68.31        
Effective interest rate (as a percent) 6.00%   6.00%