Quarterly report pursuant to Section 13 or 15(d)

Convertible Senior Notes - Narrative (Details)

v3.19.3
Convertible Senior Notes - Narrative (Details)
1 Months Ended 2 Months Ended 3 Months Ended 9 Months Ended
Aug. 16, 2019
USD ($)
Aug. 15, 2019
USD ($)
May 22, 2018
USD ($)
Jun. 30, 2019
USD ($)
Nov. 30, 2018
shares
May 31, 2018
USD ($)
d
$ / shares
shares
Aug. 31, 2014
USD ($)
d
$ / shares
shares
Aug. 31, 2018
USD ($)
Apr. 30, 2018
USD ($)
Sep. 30, 2019
USD ($)
shares
Sep. 30, 2018
USD ($)
Jun. 30, 2018
USD ($)
Sep. 30, 2019
USD ($)
shares
Sep. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
shares
Debt Instrument [Line Items]                              
Conversion option fair value                         $ 0 $ 31,571,000  
Derivative liability                   $ 0     0   $ 23,430,000
Derivative asset                   $ 0     $ 0   $ 22,576,000
Warrants repurchased (shares) | shares         525,000                    
Warrants outstanding (shares) | shares                   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             $ 245,000,000.0     $ 0     $ 0   $ 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                     563,200,000  
Increase (decrease) in if-converted value in excess of principal                     $ 161,900,000     $ 221,600,000  
Notices for conversion       $ 1,000,000.0       $ 195,900,000 $ 21,800,000            
Conversion value over the principal amount       $ 500,000       $ 439,600,000 31,600,000            
Gain (loss) on extinguishment of debt                 $ (600,000)            
Repayments of notes $ 0 $ 26,300,000                          
Debt premium $ 0 $ 11,900,000                          
Gain (loss) on derivative                         (10,200,000)    
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           $ 750,000,000.0       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%                  
Debt premium           $ 13,700,000                  
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                  
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                   $ (1,900,000)     $ (11,000,000.0)    
Warrant exercise price (USD per share) | $ / shares             $ 125.08                
Warrant derivative in connection with Notes             $ 11,600,000