Income Taxes - Components of Deferred Income Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets, Net [Abstract]
Canadian net operating losses	$ 39,574	$ 40,252
U.S. net operating losses	5,347	5,588
Research and development deductions and credits	11,062	9,588
Other	1,831	1,797
Less: valuation allowance	(57,814)	(57,225)
Net deferred income tax assets	$ 0	$ 0

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from in-process research and development costs expensed in connection with a business combination.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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