Business Segment Information - external customers by geographic region (Details) - CAD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Segment Information
Gross revenues	$ 113,267	$ 139,751	$ 274,035
Canada
Business Segment Information
Gross revenues	13,730	13,035	19,595
Africa
Business Segment Information
Gross revenues	4,114	4,254	4,283
Americas
Business Segment Information
Gross revenues	5,880	1,786	22,446
Asia
Business Segment Information
Gross revenues	1,909	1,549	14,894
Europe
Business Segment Information
Gross revenues	$ 87,634	$ 119,127	$ 212,817

Expiry date 2020-01-01: The income arising in the course of an entity's ordinary activities. Income is increases in economic benefits during the accounting period in the form of inflows or enhancements of assets or decreases of liabilities that result in an increase in equity, other than those relating to contributions from equity participants. Effective 2020-01-01: The income arising in the course of an entity's ordinary activities. Income is increases in assets, or decreases in liabilities, that result in increases in equity, other than those relating to contributions from holders of equity claims.

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+ Details