Quarterly report pursuant to Section 13 or 15(d)

Selected Balance Sheet Data - Narrative (Detail)

v3.22.2.2
Selected Balance Sheet Data - Narrative (Detail) - USD ($)
 3 Months Ended 9 Months Ended
Jan. 01, 2022
Jan. 01, 2021
Jan. 01, 2014
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2022
Sep. 30, 2021
Dec. 31, 2021
Mar. 31, 2013
Schedule Of Accrued Expenses [Line Items]                  
Advances and loans and commissions receivable allowance for credit loss       $ 836,000   $ 836,000   $ 789,000  
SARs frozen liability amount       13,002,000   $ 13,002,000   14,918,000  
Treasury note term           1 year      
Interest expense       229,000 $ 144,000 $ 547,000 $ 436,000    
Commissions Payable                  
Schedule Of Accrued Expenses [Line Items]                  
Maximum payment deferral period for certain commissions payable           3 years      
Mortgage servicing rights                  
Schedule Of Accrued Expenses [Line Items]                  
Servicing portfolio of commercial real estate loans, unpaid principal balance               $ 1,700,000,000  
SARs                  
Schedule Of Accrued Expenses [Line Items]                  
SARs frozen liability amount                 $ 20,000,000
Treasury note term     10 years            
Base spread on SARs liability variable rate     2.00%            
SARs liability interest accrual rates 3.63% 2.93%              
Interest expense       $ 135,000 $ 122,000 $ 406,000 366,000    
Payments made during the period           $ 2,200,000 2,200,000    
Deferred Compensation Liability                  
Schedule Of Accrued Expenses [Line Items]                  
Fair value of deferred compensation plan assets           110.00%      
Payments made during the period           $ 807,000 $ 1,200,000    
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