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Concentrations of Market Risk (Details) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2018 CAD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 CAD ($)
Concentration Risk [Line Items]
Total outstanding loan balance, due within 12 months			$ 700
Interest Rate Risk [Member]
Concentration Risk [Line Items]
Cash and cash equivalents and marketable securities	$ 119,306
Interest rate risk, description	The Company does not enter into investments for trading or speculative purposes and has not used any derivative financial instruments to manage interest rate exposure. A 10% change in interest rates during any of the periods presented would not have had a material impact on the Company?s consolidated financial statements.
Total outstanding loan balance	$ 15,500
Total outstanding loan balance, due within 12 months
Interest Rate Risk [Member] \| Prime Rate [Member] \| Amended And Restated Loan And Security Agreement [Member] \| Bank [Member]
Concentration Risk [Line Items]
Percentage of floating rate above prime rate	0.50%
Foreign Currency Exchange Risk [Member]
Concentration Risk [Line Items]
Cash and cash equivalents and marketable securities	$ 110,771	$ 11,644	$ 28,028	$ 19,619