Quarterly report pursuant to Section 13 or 15(d)

Selected Balance Sheet Data - Narrative (Detail)

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Selected Balance Sheet Data - Narrative (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jan. 01, 2024
Jan. 01, 2023
Jan. 01, 2014
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Dec. 31, 2023
Mar. 31, 2013
Schedule Of Accrued Expenses [Line Items]                  
Advances and loans and commissions receivable allowance for credit loss       $ 883   $ 883   $ 680  
SARs frozen liability amount       9,178   $ 9,178   $ 11,418  
Commissions Payable                  
Schedule Of Accrued Expenses [Line Items]                  
Maximum payment deferral period for certain commissions payable           3 years      
SARs                  
Schedule Of Accrued Expenses [Line Items]                  
SARs frozen liability amount                 $ 20,000
Treasury note term     10 years            
Base spread on SARs liability variable rate     2.00%            
SARs liability interest accrual rates 5.95% 5.79%              
Interest expense       $ 170 $ 190 $ 340 $ 380    
Payments for SARs Liability           $ 2,500 2,300    
Deferred Compensation Liability                  
Schedule Of Accrued Expenses [Line Items]                  
Fair value of deferred compensation plan assets           110.00%      
Payments made during the period           $ 121 $ 163    
Deferred Compensation Liability | Minimum                  
Schedule Of Accrued Expenses [Line Items]                  
Payout period           2 years      
Deferred Compensation Liability | Maximum                  
Schedule Of Accrued Expenses [Line Items]                  
Payout period           15 years