Quarterly report pursuant to Section 13 or 15(d)

Selected Balance Sheet Data - Additional Information (Detail)

v3.5.0.2
Selected Balance Sheet Data - Additional Information (Detail)
 3 Months Ended 9 Months Ended
Jan. 01, 2016
Jan. 01, 2015
Jan. 01, 2014
Sep. 30, 2016
USD ($)
Sep. 30, 2015
USD ($)
Sep. 30, 2016
USD ($)
Installments
Sep. 30, 2015
USD ($)
Dec. 31, 2015
USD ($)
Mar. 31, 2013
USD ($)
Schedule Of Accrued Expenses [Line Items]                  
SARs frozen liability amount       $ 20,719,000   $ 20,719,000   $ 21,399,000  
Interest expense       380,000 $ 380,000 $ 1,155,000 $ 1,349,000    
Maximum payment deferral period for certain commissions payable           3 years      
SARs [Member]                  
Schedule Of Accrued Expenses [Line Items]                  
SARs frozen liability amount                 $ 20,000,000
SARs liability frozen value date           Mar. 31, 2013      
SARs liability interest accrual commencement date           Jan. 01, 2014      
Interest expense       $ 229,000 $ 214,000 $ 686,000 $ 642,000    
Treasury note term     10 years            
Base spread on SARs liability variable rate     2.00%            
SARs liability interest accrual rates 4.273% 4.173%              
SARs liability number of annual installments | Installments           10      
Estimated payouts description           Estimated payouts within the next twelve months for participants that have separated from service have been classified as current.      
Deferred Compensation Liability [Member]                  
Schedule Of Accrued Expenses [Line Items]                  
Estimated payouts description           Estimated payouts within the next twelve months for participants that have separated from service have been classified as current.      
Deferred Compensation Liability, Minimum Payout Period           2 years      
Deferred Compensation Liability, Maximum Payout Period           15 years      
Fair value of deferred compensation plan assets           110.00%