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Stock-Based Compensation - Narrative (Details) - USD ($)
9 Months Ended 12 Months Ended
Jul. 23, 2019
Sep. 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares available for grant (in shares)     615,234    
Service period (in years)     4 years    
Weighted-average grant date fair value of option (in USD per share)     $ 9.31 $ 5.30 $ 5.14
Shares exercised in period (in shares)     $ 6,500,000 $ 10,900,000 $ 100,000
Total grant-date fair value of stock options vested     8,100,000 $ 3,300,000 3,600,000
Nonvested award options, unrecognized compensation expense     $ 16,200,000    
Shares issued to former employees with notes determined to be nonrecourse (in shares)     52,778    
Options          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Nonvested awards, period for recognition     2 years 3 months 18 days    
Restricted stock units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Service period (in years)   4 years      
Nonvested awards, period for recognition   3 years 4 months 24 days      
Vesting period   1 year      
Unrecognized stock-based compensation expense     $ 16,900,000    
Employee stock purchase plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares authorized for grant (in shares)     750,000    
Percentage increase of the number of common stock shares (in percentage)     1.00%    
Total grant-date fair value of stock options vested     $ 3,000,000.0    
Amount of shares to be increased by (in shares)     750,000    
Maximum employee subscription rate (in percentage)     15.00%    
Maximum purchase value during offering Period per employee     $ 25,000    
Maximum purchased shares allowed (in shares)     2,500    
Purchase price of common stock (in percentage)     85.00%    
Shares issued in period (in shares)     134,766    
Per share weighted average price of shares purchased (in USD per share)     $ 22.10    
Stock Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares authorized for grant (in shares) 2,756,607   11,272,878 8,772,878  
Shares available for grant (in shares)     2,309,370 1,296,793  
Stock Incentive Plan | Performance shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Service period (in years)     4 years    
Cumulative catch-up compensation expense     $ 6,000,000.0    
Shares exercised in period (in shares)       $ 100,000 $ 100,000
Stock Incentive Plan 2011          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of additional shares authorized (in shares) 256,607        
Percentage increase of the number of common stock shares (in percentage) 5.00%        
Stock Incentive Plan 2019          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares authorized for grant (in shares) 2,500,000