Leases - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
Cumulative effect of new accounting principle in period of adoption			$ 5,500
Operating lease liabilities	$ 1,295	$ 1,295	1,600
Operating lease liabilities, long-term	4,011	4,011	$ 3,900
Lease expense recognize on a straight-line basis	500	1,600
2019	500	500		$ 2,000
2020	1,615	1,615		1,500
2021	811	811		800
2022	477	477		500
2023	355	355		400
After 2023	$ 3,738	$ 3,738		$ 4,200