Accounts Payable and Accrued Expenses - Schedule of Accounts Payable and Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Payables and Accruals [Abstract]
Accounts payable	$ 3,934		$ 3,096
Accrued inventories in-transit	411		1,207
Accrued other miscellaneous expenses	2,836		2,412
Advanced deposits	890		0
Accrued compensation	3,424		3,605
Income taxes payable	2,049		536
Accrued warranty	1,760	$ 1,752	1,769	$ 1,852	$ 2,026	$ 2,344
Total	$ 15,304		$ 12,625