Leases - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Leases [Abstract]
Operating lease term	5 years		5 years
Rental expense for operating leases		$ 1,100,000		$ 2,000,000
Right-of-use asset	$ 7,425,000		$ 7,425,000
Operating lease liabilities	9,605,000		9,605,000
Cash paid for lease liabilities for operating leases			600,000
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 7 months 28 days		4 years 7 months 28 days
Weighted average discount rate	8.61%		8.61%