Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Statutory rate	21.00%	34.00%	34.00%
Income tax expense (benefit)	$ (312,000)	$ (134,000)
Income tax deficiencies with restricted stock and stock options		100,000
Adjustments related to transition tax	$ 0
Designed to tax global intangible low taxed income, minimum percentage return on depreciable tangible assets.	10.00%
Deferred tax assets, net of deferred tax liabilities	$ 8,100,000		$ 7,700,000
Operating loss and credit carry forward, expiration period	The Company’s net operating losses and credits have a finite life primarily based on the 20-year carry forward of federal net operating losses generated as of December 31, 2017.
Net operating loss carry forward period	20 years
Domestic deferred tax assets ratable reversal pattern period	13 years
Deferred tax assets, valuation allowance	$ 5,200,000		5,200,000
Gross unrecognized tax benefit	$ 700,000		$ 700,000
Research Tax Credit Carryforward [Member]
Income Tax Disclosure [Line Items]
Tax benefit related to previously unrecognized tax benefits		$ 100,000