Leases - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating lease option to extend	options to extend the leases for up to 10 years, and some of which include options to terminate the leases within 1 year.
Sublease Income	$ 39,000
Sublease option to terminate	sublease expires in 2022 with an option to terminate and no option to extend.
Lease expense	$ 2,744,000	$ 2,601,000	$ 2,608,000
Lease rental income	419,000	373,000	321,000
Barry R Sloane [Member]
Lease expense	$ 458,000	$ 444,000	$ 439,000
Maximum [Member]
Operating lease remaining lease term	32 years
Minimum [Member]
Operating lease remaining lease term	1 year