Annual report pursuant to Section 13 and 15(d)

Debt (Conv) (Details)

v3.6.0.2
Debt (Conv) (Details) - Convertible Notes
 12 Months Ended
Dec. 15, 2014
USD ($)
item
$ / shares
Dec. 31, 2016
USD ($)
$ / shares
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Debt        
Face amount $ 172,500,000      
Net proceeds from offering $ 166,967,000      
Interest rate (as a percent) 1.75% 1.75%    
Repurchase percentage of principal (as a percent) 100.00%      
Conversion rate 0.0159022      
Principal amount | $ / shares $ 1,000      
Conversion price (in dollars per share) | $ / shares $ 62.88 $ 62.88    
Threshold trading days (in days) | item 20      
Consecutive trading days 30 days      
Threshold percentage of stock price trigger (as a percent) 130.00%      
Threshold business days 5 days      
Threshold consecutive trading-day period 5 days      
Threshold percentage of trading price trigger (as a percent) 98.00%      
Allocated to equity components $ 26,618,000      
Offering costs 882,000      
Discount $ 27,500,000 $ 17,149,000 $ 22,367,000  
Accretion of debt discount   $ 5,218,000 $ 4,932,000  
Effective interest rate on the liability component (as a percent)   6.00%    
Other non-current assets        
Debt        
Issuance costs       $ 4,651,000