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Benefit Plans - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Jun. 08, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense $ 7,666,000 $ 5,549,000 $ 5,892,000    
Tax benefit related to share-based compensation expense 2,100,000 1,500,000 1,600,000    
Capitalized share-based compensation expense $ 0 $ 0 $ 0    
Stock option plans remain outstanding 274,630 409,410 580,140 845,600  
Number of options, granted 0 0 0    
Eligible period of service for participation in plan 2 months        
Minimum age for employees to participate in KSOP 21 years        
Dividends deducted $ 400,000        
Tax benefit from dividends $ 100,000        
Shares outstanding, employee stock ownership plan 245,780        
Percentage of total common shares outstanding 1.00%        
Stock Options [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of additional shares authorized 1,414,352        
Stock options granted 8,458,600        
Stock options, exercise prices lower $ 3.47        
Stock options, exercise prices upper $ 40.37        
Purchase of shares 6,511,238        
Stock option shares terminated 1,672,732        
Stock option plans remain outstanding 274,630        
Stock options outstanding, exercise prices lower $ 24.60        
Stock options outstanding, exercise prices upper $ 40.37        
Stock options vesting period 5 years        
Options Outstanding, Weighted-Average Remaining Contractual Life (Years) 7 years        
Options issued to non-employee advisors 0        
Aggregate intrinsic value of options exercised and sold $ 16,200,000 $ 11,900,000 $ 9,100,000    
Total unrecognized compensation cost $ 100,000        
Performance-based RSUs [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock options vesting period 3 years     5 years  
Percentage of vesting annually at anniversary       20.00%  
Number of RSU's expected to vest 116,989        
Performance-based RSUs [Member] | Vesting after three years [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Percentage of vesting RSUs 100.00%     60.00%  
Service-based RSUs [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of RSU's expected to vest 111,631        
Number of forfeitures expected 0        
Restricted Stock Units [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Expected recognition period of unrecognized compensation expense 1 year 4 months 24 days        
Number of forfeitures expected 8,646 7,593 840    
Total fair value of RSU's vested based on weighted average grant date values $ 6,200,000 $ 3,900,000 $ 1,200,000    
Stock-based compensation expense for restricted stock 7,300,000 $ 4,600,000 $ 4,700,000    
Total unrecognized compensation expense net of forfeitures $ 14,800,000        
Maximum [Member] | Stock Options [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Expected recognition period of unrecognized compensation expense 1 year        
Maximum [Member] | Service-based RSUs [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock options vesting period 14 months        
Minimum [Member] | Service-based RSUs [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock options vesting period 12 months        
2016 Stock Incentive Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Reduction in common stock available for grant 2        
Common Stock [Member] | 2016 Stock Incentive Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares of common stock remained available for grants of awards         2,000,000
Common Stock [Member] | 2016 Stock Incentive Plan [Member] | Maximum [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Term of award (in years) 7 years        
Common Stock [Member] | 2016 Stock Incentive Plan [Member] | Minimum [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Rate of exercise price for equity award granted 100.00%