v3.21.2
Convertible Senior Notes - 0.75% Convertible Notes due 2023 Narrative (Details)
$ / shares in Units, shares in Millions
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
May 31, 2021
USD ($)
Nov. 30, 2020
USD ($)
shares
Feb. 28, 2018
USD ($)
Sep. 30, 2021
USD ($)
note
$ / shares
Jun. 30, 2021
USD ($)
Mar. 31, 2021
day
Sep. 30, 2020
USD ($)
Jun. 30, 2018
day
Sep. 30, 2021
USD ($)
day
note
$ / shares
Sep. 30, 2020
USD ($)
Dec. 31, 2020
USD ($)
day
Debt Instrument [Line Items]                      
Loss on extinguishment of debt       $ 0     $ 0   $ 1,513,000 $ 0  
Payments for repurchases of convertible notes                 $ 63,692,000 $ 0  
Shares subject to warrants related to the issuance of the 2023 Notes                      
Debt Instrument [Line Items]                      
Unamortized debt issuance costs   $ 2,000,000     $ 300,000            
Remaining amortization period for debt discount and debt issuance costs                 1 year 4 months 24 days    
Shares subject to warrants related to the issuance of the 2023 Notes | Convertible Debt                      
Debt Instrument [Line Items]                      
Interest rate     0.75%                
Principal amount     $ 230,000,000 10,900,000         $ 10,900,000    
Initial conversion rate of common stock     0.0174292                
Principal amount exchanged   181,900,000                  
Carrying value $ 10,000,000 $ 42,900,000   10,068,000         10,068,000   $ 42,619,000
Loss on extinguishment of debt         $ 1,500,000           8,900,000
Unamortized debt issuance costs       $ 76,000         $ 76,000   $ 501,000
Repurchased principal amount 37,100,000                    
Payments for repurchases of convertible notes $ 63,700,000                    
Limitation on sale of common stock, sale price threshold, number of trading days | day           20   20     20
Limitation on sale of common stock, sale price threshold, trading period | day           30   30 30   30
Threshold percentage of stock price trigger           130.00%   130.00% 130.00%   130.00%
Number of consecutive business days     5 days                
Percentage of closing sale price in excess of convertible notes     98.00%                
Redemption price percentage     100.00%                
If-converted value of convertible note that exceed principal amount                 $ 4,300,000    
Closing price of common stock (in dollars per share) | $ / shares       $ 80.14         $ 80.14    
Number of notes converted | note       22         22    
Effective interest rate of liability component     5.875%                
Issuance costs attributable to the liability component     $ 5,300,000                
Net issuance costs related to the equity component     $ 1,500,000                
Shares subject to warrants related to the issuance of the 2023 Notes | Convertible Debt | Bond Hedge                      
Debt Instrument [Line Items]                      
Conversion price (usd per share) | $ / shares       $ 57.38         $ 57.38    
Convertible Notes Due 2025                      
Debt Instrument [Line Items]                      
Remaining amortization period for debt discount and debt issuance costs                 4 years 1 month 6 days    
Convertible Notes Due 2025 | Convertible Debt                      
Debt Instrument [Line Items]                      
Interest rate   0.125%                  
Principal amount   $ 350,000,000                  
Initial conversion rate of common stock   0.0071355                  
Conversion price (usd per share) | $ / shares       $ 140.14         $ 140.14    
Principal amount received   $ 210,700,000                  
Shares issued from exchange on convertible senior notes (in shares) | shares   1.3                  
Carrying value       $ 282,630,000         $ 282,630,000   $ 271,690,000
Unamortized debt issuance costs       $ 4,476,000         $ 4,476,000   $ 5,235,000
Limitation on sale of common stock, sale price threshold, number of trading days | day                 20    
Limitation on sale of common stock, sale price threshold, trading period | day                 30    
Threshold percentage of stock price trigger                 130.00%    
Number of consecutive business days                 5 days    
Percentage of closing sale price in excess of convertible notes                 98.00%    
Redemption price percentage   100.00%                  
Effective interest rate of liability component       5.00%         5.00%    
Issuance costs attributable to the liability component   $ 5,400,000                  
Net issuance costs related to the equity component   $ 1,500,000