Income Taxes - Net Deferred Income Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets
Scientific research and experimental development pool	$ 25,056	$ 22,823
Investment tax credits	22,872	22,483
Non-capital losses	13,645	7,800
Depreciable assets	5,360	4,163
Deferred financing fees	578	1,020
Other	114	126
Less - valuation allowance	$ (67,625)	$ (58,415)

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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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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