Leases - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Leases [Abstract]
Operating lease term	5 years		5 years
Rental expense for operating leases		$ 1,200,000		$ 3,100,000
Right-of-use asset	$ 7,043,000		$ 7,043,000
Operating lease liabilities	9,146,000		9,146,000
Cash paid for lease liabilities for operating leases	600,000		1,900,000
Right-of-use assets obtained in exchange for operating lease obligations	0		100,000
Operating lease obligations	$ 0		$ 100,000
Weighted average remaining operating lease term	4 years 5 months 8 days		4 years 5 months 8 days
Weighted average discount rate	8.60%		8.60%