Income Taxes - Net Deferred Income Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax assets
Scientific research and experimental development pool	$ 26,572	$ 25,056
Investment tax credits	23,808	22,872
Non-capital losses	22,035	13,645
Depreciable assets	5,710	5,360
Deferred financing fees	1,303	578
Other	98	114
Less - valuation allowance	$ (79,526)	$ (67,625)

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