Annual report pursuant to Section 13 and 15(d)

Debt (Convertible Notes) (Details)

v3.19.3.a.u2
Debt (Convertible Notes) (Details)
1 Months Ended 12 Months Ended
Dec. 15, 2019
USD ($)
May 25, 2018
USD ($)
days
$ / shares
Dec. 15, 2014
USD ($)
$ / shares
May 31, 2018
USD ($)
Dec. 31, 2019
USD ($)
$ / shares
Dec. 31, 2018
USD ($)
$ / shares
Dec. 31, 2017
USD ($)
Dec. 31, 2014
USD ($)
Debt Instrument [Line Items]                
Face amount     $ 172,500,000          
Net proceeds from offering     $ 166,967,000          
Interest rate     1.75%          
Conversion rate     0.0159022          
Conversion price (in dollars per share) | $ / shares     $ 62.88          
Allocated to equity components   $ 46,611,000 $ 26,618,000          
Offering costs   1,389,000 882,000          
Discount   $ 48,000,000 $ 27,500,000          
Accretion of debt discount         $ (15,040,000) $ (11,134,000) $ (5,472,000)  
Effective interest rate         4.00%      
Repayments of convertible debt $ 184,751,000       $ 184,751,000 0 0  
Premium payable $ 12,251,000              
Threshold percentage of trading price trigger   98.00%            
Other non-current assets                
Debt Instrument [Line Items]                
Issuance costs               $ 4,651,000
Convertible Notes Due 2019                
Debt Instrument [Line Items]                
Face amount         $ 0 $ 172,500,000    
Interest rate     1.75%          
Conversion price (in dollars per share) | $ / shares         $ 68.31 $ 62.88    
Discount         $ 0 $ 5,890,000    
Accretion of debt discount         $ (5,890,000) $ (5,690,000) $ (5,472,000)  
Effective interest rate         6.00% 6.00% 6.00%  
Convertible Notes Due 2023                
Debt Instrument [Line Items]                
Face amount   $ 345,000,000     $ 345,000,000 $ 345,000,000    
Net proceeds from offering       $ 335,018,000        
Issuance costs         8,593,000      
Interest rate   1.75%            
Conversion rate   0.0146381            
Conversion price (in dollars per share) | $ / shares   $ 68.31            
Discount         33,491,000 42,641,000    
Accretion of debt discount         $ 9,150,000 $ 5,444,000    
Effective interest rate         6.00% 6.00%    
Repurchase percentage of principal   100.00%            
Threshold trading days | days   20            
Consecutive trading days | days   30            
Threshold percentage of stock price trigger   130.00%            
Threshold business days     5 days          
Threshold consecutive trading-day period     5 days