Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes Disclosure [Line Items]
Expected Canadian income tax rate	27.00%
Expected U.S. income tax rates	27.98%
Combined Canadian and US expected income tax rates	(27.30%)	(27.90%)	(27.30%)
Reduction in net deferred tax assets as per Tax Cuts and Jobs Act		$ 2,300,000
Uncertain tax position	Less than a 50%
Unrecognized tax benefits	$ 0
Income tax examination, description	The Company currently files income tax returns in the United States and Canada, the jurisdictions in which the Company believes that it is subject to tax. Further, while the statute of limitations in each jurisdiction where an income tax return has been filed generally limits the examination period, as a result of loss carry-forwards, the limitation period for examination generally does not expire until several years after the loss carry-forwards are utilized. Other than routine audits by tax authorities for tax credits and tax refunds that the Company has claimed, the Company is not aware of any other material income tax examination currently in progress by any taxing jurisdiction.
Domestic Tax Authority [Member]
Income Taxes Disclosure [Line Items]
Net operating losses carried forward for tax purposes	$ 21,800,000	$ 15,200,000
Tax Cuts and Jobs Act [Member]
Income Taxes Disclosure [Line Items]
Federal corporate tax	21.00%	35.00%
Canada [Member] | Minimum [Member]
Income Taxes Disclosure [Line Items]
Operating loss carry forwards, expiration dates	2025
Canada [Member] | Maximum [Member]
Income Taxes Disclosure [Line Items]
Operating loss carry forwards, expiration dates	2038
Canada [Member] | Foreign Tax Authority [Member]
Income Taxes Disclosure [Line Items]
Net operating losses carried forward for tax purposes	$ 149,100,000	$ 131,900,000
Tax deductions for scientific research and experimental development	19,700,000	16,800,000
Canada [Member] | Foreign Tax Authority [Member] | Investment Tax Credit Carryforward [Member]
Income Taxes Disclosure [Line Items]
Investment tax credits available to offset Canadian federal	$ 5,200,000	4,500,000
Canada [Member] | Foreign Tax Authority [Member] | Investment Tax Credit Carryforward [Member] | Minimum [Member]
Income Taxes Disclosure [Line Items]
Investment tax credits available to offset Canadian taxes, expiration dates	2019
Canada [Member] | Foreign Tax Authority [Member] | Investment Tax Credit Carryforward [Member] | Maximum [Member]
Income Taxes Disclosure [Line Items]
Investment tax credits available to offset Canadian taxes, expiration dates	2037
California [Member] | Domestic Tax Authority [Member]
Income Taxes Disclosure [Line Items]
Net operating losses carried forward for tax purposes	$ 14,600,000	$ 8,000,000