Fair Value of Financial Assets and Liabilities - Summary of Assets and Liabilities Recorded and Measured at Fair Value (Detail) $ in Thousands	Sep. 30, 2018 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	$ 1,782
Total Assets	1,782
Supplemental profit sharing plan	4,759
Total Liabilities	4,759
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	1,782
Total Assets	1,782
Supplemental profit sharing plan	0
Total Liabilities	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0
Total Assets	0
Supplemental profit sharing plan	4,759
Total Liabilities	4,759
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0
Total Assets	0
Supplemental profit sharing plan	0
Total Liabilities	$ 0