Fair Value of Financial Assets and Liabilities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments in marketable securities	$ 4,690,000	$ 0	$ 0
Marketable securities	1,648,000
Supplemental profit sharing plan	4,946,000
Fair value liabilities Level 2	0
Profit Sharing Plan [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Supplemental profit sharing plan	4,900,000	$ 4,800,000
Corporate Owned Life Insurance Policy [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	3,000,000
Corporate Owned Life Insurance Policy [Member] | Other Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash surrender value	2,800,000
Maximum [Member] | Other Income [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain loss on change in fair value of securities	$ 100,000