Quarterly report pursuant to Section 13 or 15(d)

Convertible Senior Notes - Narrative (Details)

v3.19.2
Convertible Senior Notes - Narrative (Details)
1 Months Ended 2 Months Ended 3 Months Ended 6 Months Ended
May 22, 2018
USD ($)
Jun. 30, 2019
USD ($)
$ / shares
shares
Nov. 30, 2018
shares
May 31, 2018
USD ($)
d
$ / shares
shares
Aug. 31, 2014
USD ($)
d
$ / shares
shares
Aug. 31, 2018
USD ($)
Apr. 30, 2018
USD ($)
Jun. 30, 2019
USD ($)
$ / shares
shares
Jun. 30, 2018
USD ($)
Jun. 30, 2019
USD ($)
$ / shares
shares
Jun. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
shares
Debt Instrument [Line Items]                        
Conversion option fair value                   $ 0 $ 31,571,000  
Derivative liability   $ 14,313,000           $ 14,313,000   14,313,000   $ 23,430,000
Derivative asset   $ 14,313,000           $ 14,313,000   $ 14,313,000   $ 22,576,000
Warrants repurchased (shares) | shares     525,000                  
Warrants outstanding (shares) | shares   2,739,643           2,739,643   2,739,643   2,739,643
2023 Convertible Senior Notes                        
Debt Instrument [Line Items]                        
Warrant derivative in connection with Notes                 $ 97,805,000      
Convertible Notes | 2019 Convertible Senior Notes                        
Debt Instrument [Line Items]                        
Aggregate principal amount outstanding   $ 27,323,000     $ 245,000,000.0     $ 27,323,000   $ 27,323,000   $ 27,326,000
Effective interest rate (as a percent)         5.83%              
Initial conversion rate (shares per $1,000)         0.0133251              
Initial conversion price (USD per share) | $ / shares         $ 75.05              
Interest rate (as a percent)         0.75%              
Conversion option fair value $ 341,600,000                   401,300,000  
Increase (decrease) in if-converted value in excess of principal                     $ 59,700,000  
Notices for conversion   1,000,000.0       $ 195,900,000 $ 21,800,000          
Conversion value over the principal amount           $ 439,600,000 31,600,000          
Gain (loss) on extinguishment of debt             $ (600,000)          
Derivative liability   $ 14,300,000           $ 14,300,000   $ 14,300,000    
Exercise price of convertible bond hedge (USD per share) | $ / shares   $ 75.05           $ 75.05   $ 75.05    
Gain (loss) on derivative               $ (4,400,000)   $ (9,100,000)    
Convertible Notes | 2019 Convertible Senior Notes | Debt Instrument, Redemption, Period One                        
Debt Instrument [Line Items]                        
Threshold trading days | d         20              
Consecutive trading days | d         30              
Stock price trigger to classify convertible debt as current (as a percent)         130.00%              
Convertible Notes | 2019 Convertible Senior Notes | Debt Instrument, Redemption, Period Two                        
Debt Instrument [Line Items]                        
Threshold trading days | d         5              
Consecutive trading days | d         10              
Maximum threshold of debt trading price trigger (as a percent)         98.00%              
Convertible Notes | 2023 Convertible Senior Notes                        
Debt Instrument [Line Items]                        
Aggregate principal amount outstanding   $ 750,000,000   $ 750,000,000.0       750,000,000   750,000,000   $ 750,000,000
Initial conversion rate (shares per $1,000)       0.0040244                
Initial conversion price (USD per share) | $ / shares       $ 248.48                
Interest rate (as a percent)       0.75%                
Warrants issued in public offering (shares) | shares       3,018,327                
Payments for convertible bond hedges       $ 140,300,000                
Warrant exercise price (USD per share) | $ / shares       $ 315.38                
Warrant derivative in connection with Notes       $ 90,000,000.0                
Proceeds from debt, net of issuance costs       733,100,000                
Debt issuance costs       16,900,000                
Debt issuance costs related to the liability component of convertible debt       $ 13,700,000                
Convertible Notes | 2023 Convertible Senior Notes | Debt Instrument, Redemption, Period One                        
Debt Instrument [Line Items]                        
Threshold trading days | d       20                
Consecutive trading days | d       30                
Stock price trigger to classify convertible debt as current (as a percent)       130.00%                
Convertible Notes | 2023 Convertible Senior Notes | Debt Instrument, Redemption, Period Two                        
Debt Instrument [Line Items]                        
Threshold trading days | d       5                
Consecutive trading days | d       10                
Maximum threshold of debt trading price trigger (as a percent)       98.00%                
Convertible Bond Hedges | 2019 Convertible Senior Notes                        
Debt Instrument [Line Items]                        
Warrants issued in public offering (shares) | shares         3,264,643              
Exercise price of convertible bond hedge (USD per share) | $ / shares         $ 75.05              
Payments for convertible bond hedges         $ 48,100,000              
Gain (loss) on derivative               $ 4,400,000   $ 8,300,000    
Warrant exercise price (USD per share) | $ / shares         $ 125.08              
Warrant derivative in connection with Notes         $ 11,600,000