Leases - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($) Lease	Mar. 31, 2019 USD ($)
Lessee Lease Description [Line Items]
Operating lease expense	$ 233,000	$ 460,000
Operating lease, ROU asset	4,410,000	4,410,000
Operating lease liability	4,732,000	$ 4,732,000
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	$ 3,500,000
Operating lease liability	3,800,000	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	478,000
Operating lease liability	$ 473,000	$ 473,000
ASU 2016-02 | Minimum
Lessee Lease Description [Line Items]
Operating lease term		1 year
ASU 2016-02 | Maximum [Member]
Lessee Lease Description [Line Items]
Operating lease term		10 years
Operating lease, renewal term	5 years	5 years