Quarterly report pursuant to Section 13 or 15(d)

Debt (Convertible) (Details)

v3.8.0.1
Debt (Convertible) (Details) - Convertible Notes
$ / shares in Units, $ in Thousands
Dec. 15, 2014
USD ($)
$ / shares
Mar. 31, 2018
$ / shares
Mar. 31, 2017
Debt      
Face amount and over allotments | $ $ 172,500    
Interest rate (as a percent) 1.75%    
Repurchase percentage of principal (as a percent) 100.00%    
Conversion rate 15.9022    
Principal amount $ 1    
Conversion price (in dollars per share) $ 62.88 $ 62.88  
Effective interest rate (as a percent)   6.00% 6.00%