Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation - Activity (Details)

v3.19.3.a.u2
Share-Based Compensation - Activity (Details) - USD ($)
3 Months Ended 12 Months Ended
Feb. 19, 2018
Feb. 21, 2017
Mar. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Feb. 18, 2019
Unrecognized share-based compensation expense            
Restricted stock awards, Unrecognized compensation expense       $ 8,221,000    
Restricted stock awards, Weighted average remaining vesting period       1 year    
Stock options, Unrecognized compensation expense       $ 1,524,000    
Stock options, Weighted average remaining vesting period       8 months 12 days    
Total unrecognized compensation expense related to unvested awards       $ 9,745,000    
Restricted Stock Awards            
Restricted Stock Awards, Number of Shares            
Balance at beginning of period (in shares)     411,600 499,200    
Granted (in shares)       250,600    
Converted/Exercised (in shares)       (312,400)    
Forfeited (in shares)       (25,800)    
Balance at end of period (in shares)       411,600 499,200  
Restricted Stock Awards, Weighted Average Grant Date Fair Value Per Share            
Balance at beginning of period (in dollars per share)     $ 57.51 $ 41.29    
Granted (in dollars per share)       67.37    
Converted/Exercised (in dollars per share)       30.96    
Forfeited (in dollars per share)       58.65    
Balance at end of period (in dollars per share)       $ 57.51 $ 41.29  
Assumptions used to estimate the fair values of the awards granted:            
Measurement period (years)       2 years 10 months 13 days 2 years 10 months 13 days  
Risk free interest rate (as a percent)       2.50% 2.36%  
Dividend yield (as a percent)       0.00% 0.00%  
Estimated fair value of market-based RSAs at grant date (in dollars per share)       $ 80.74 $ 103.31  
Stock Options            
Stock Options, Number of Shares            
Balance at beginning of period (in shares)     373,500 611,400    
Granted (in shares)       103,500    
Converted/Exercised (in shares)       (329,000.0)    
Forfeited (in shares)       (9,700)    
Expired (in shares)       (2,700)    
Balance at end of period (in shares)       373,500 611,400  
Stock Options, Weighted Average Grant Date Fair Value Per Share            
Balance at beginning of period (in dollars per share)     $ 17.06 $ 13.10    
Granted (in dollars per share)       21.16    
Converted/Exercised (in dollars per share)       10.91    
Forfeited (in dollars per share)       $ 20.28    
Expired (in dollars per share)       14.44    
Balance at end of period (in dollars per share)       $ 17.06 $ 13.10  
Stock Options, Weighted Average Exercise Price Per Share            
Balance at beginning of period (in dollars per share)     $ 45.90 34.45    
Granted (in dollars per share)       58.08    
Converted/Exercised (in dollars per share)       28.26    
Forfeited (in dollars per share)       54.62    
Expired (in dollars per share)       38.39    
Balance at end of period (in dollars per share)       $ 45.90 $ 34.45  
Stock options, additional disclosures            
Aggregate intrinsic value       $ 21,356,400 $ 8,685,800  
Converted/Exercised aggregate intrinsic value       $ 18,556,900    
Exercisable, Number of shares       73,900    
Exercisable, Weighted Average Grant Date Fair Value Per Share       $ 16.10    
Exercisable Weighted Average Exercise Price Per Share       $ 42.98    
Exercisable, Aggregate Intrinsic Value       $ 4,438,700    
Weighted average remaining contractual term for vested stock options       6 years 10 months 24 days    
Assumptions used to estimate the fair values of the awards granted:            
Risk free interest rate (as a percent)       2.59% 2.78%  
Expected volatility using historical return volatility and implied volatility (as a percent)       32.50% 32.50%  
Expected life (in years)       6 years 6 years  
Dividend yield (as a percent)       0.00% 0.00%  
Estimated fair value of market-based RSAs at grant date (in dollars per share)       $ 21.16 $ 27.44  
Performance-based conditions | Restricted Stock Awards            
Restricted stock awards, additional disclosures            
Grant date fair value $ 2,052,000 $ 1,816,000        
Related expenses           $ 2,488,000
Performance-based conditions | Restricted Stock Awards | Payout Range-0%            
Restricted stock awards, additional disclosures            
Payout range (as a percent) 0.00% 0.00%       0.00%
Performance-based conditions | Restricted Stock Awards | Payout Range-25%            
Restricted stock awards, additional disclosures            
Payout range (as a percent) 25.00% 25.00%       25.00%
Related expenses $ 513,000 $ 454,000       $ 622,000
Performance-based conditions | Restricted Stock Awards | Payout Range-100%            
Restricted stock awards, additional disclosures            
Payout range (as a percent) 100.00% 100.00%       100.00%
Related expenses $ 2,052,000 $ 1,816,000       $ 2,488,000
Performance-based conditions | Restricted Stock Awards | Payout Range-200%            
Restricted stock awards, additional disclosures            
Payout range (as a percent) 200.00% 200.00%       200.00%
Related expenses $ 4,104,000 $ 3,632,000       $ 4,976,000
Performance-based conditions | RSAs granted on February 21, 2017 | Subsequent Event            
Restricted stock awards, additional disclosures            
Cumulative period of achievement     3 years      
Cumulative achievement percentage     200.00%      
Total compensation expense recognized over the performance period, net of forfeitures     $ 3,300,000