Leases - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Lessee Lease Description [Line Items]
Total lease expense	$ 354,000		$ 728,000
Rent expense		$ 435,000		$ 720,000
Lessee, Operating Lease, Existence of Option to Extend [true false]			true
Weighted average remaining operating lease term	3 years 7 months 6 days		3 years 7 months 6 days
Weighted average discount rate of operating lease	6.40%		6.40%
Sublease rental income due in future under non-cancelable subleases	$ 2,200,000		$ 2,200,000
Operating lease liabilities, cash paid	500,000		1,100,000
Sublease rental income	$ 200,000		$ 400,000
Minimum
Lessee Lease Description [Line Items]
Remaining lease term			1 year
Maximum
Lessee Lease Description [Line Items]
Remaining lease term			7 years
Operating leases, options to extend leases term	5 years		5 years