Income Taxes - Schedule of Deferred Tax Assets And Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Components of Deferred Tax Assets and Liabilities [Abstract]
Net operating losses	$ 16,372	$ 9,252
Stock-based compensation	2,747	2,691
Financing lease obligations	4,009	2,131
Tax credit carry forwards	922	735
Compensation and employee benefits	474	576
Other	116	8
Gross deferred tax assets	24,640	15,393
Less valuation allowance	(20,329)	(12,792)
Net deferred tax assets	4,311	2,601
Fixed assets	(4,352)	(2,600)
Other	41	(1)
Gross deferred tax liabilities	(4,311)	(2,601)
Net deferred tax asset or liability	$ 0	$ 0