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Convertible Senior Notes - Narrative (Details)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Feb. 13, 2020
USD ($)
D
$ / shares
Mar. 31, 2021
USD ($)
D
Mar. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
Debt        
Equity component of transaction costs for 2020 Convertible Notes     $ 1,773  
Amortization period of debt discount       6 years
Initial carrying amount of the liability component       $ 97,200
Carrying amount of the equity component       46,550
Convertible senior notes, net carrying value   $ 139,286   99,575
Accumulated deficit   (312,197)   (333,147)
Additional paid-in capital   482,197   519,143
Adjustment | Accounting Standards Update 2020-06        
Debt        
Convertible senior notes, net carrying value       39,489
Accumulated deficit       (5,288)
Additional paid-in capital       $ (44,777)
Convertible senior notes        
Debt        
Interest rate (as a percent) 2.625%      
Aggregate principal amount $ 143,750      
Total debt issuance cost 5,473      
Equity component of transaction costs for 2020 Convertible Notes 1,773      
Debt discount $ 3,700      
Amortization period of debt discount 6 years      
Initial conversion rate 34.2618      
Conversion, threshold percentage of stock price trigger | $ / shares $ 29.19      
Conversion, threshold percentage of stock price trigger 130.00%      
Conversion, threshold trading days | D 20      
Conversion, threshold consecutive trading days | D 30      
Consecutive business days | D 5      
Measurement period | D 10      
Threshold percentage to product of sale price of common stock and conversion rate 98.00%      
Default period 30 days      
Threshold amount of money borrowed $ 20,000      
Convertible senior notes, net carrying value   $ 139,286    
Convertible senior notes | Conversion of convertible debt after the calendar quarter ending on march 31, 2020        
Debt        
Conversion, threshold percentage of stock price trigger   130.00%    
Conversion, threshold trading days | D   20    
Conversion, threshold consecutive trading days | D   30