Leases - Additional Information (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($) Lease	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)
Lessee Lease Description [Line Items]
Operating lease expense	$ 225,000	$ 685,000
Operating lease, ROU asset	4,222,000	4,222,000
Operating lease liability	4,521,000	$ 4,521,000
Lessee operating lease not yet commenced, option to extend		true
ASU 2016-02
Lessee Lease Description [Line Items]
Number of operating leases identified | Lease		16
Operating lease, option to extend		true
Operating lease, ROU asset					$ 3,500,000
Operating lease liability					$ 3,800,000
Minimum fair value threshold for lease contract	$ 7,500	$ 7,500
ASU 2016-02 | Richmond, Virginia
Lessee Lease Description [Line Items]
Operating lease, ROU asset				$ 826,000
Operating lease liability				$ 826,000
ASU 2016-02 | Henrico County, Virginia
Lessee Lease Description [Line Items]
Operating lease, ROU asset			$ 478,000
Operating lease liability			$ 473,000
ASU 2016-02 | Minimum
Lessee Lease Description [Line Items]
Operating lease term		1 year
ASU 2016-02 | Maximum
Lessee Lease Description [Line Items]
Operating lease term		10 years
Operating lease, renewal term	5 years	5 years