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Costs incurred and estimated earnings net of billings on uncompleted contracts (Details) - CAD	Dec. 31, 2017	Dec. 31, 2016
Costs in excess of billings [Abstract]
Costs incurred and estimated earnings on uncompleted contracts	CAD 199,863,000	CAD 208,030,000
Less billings to date	(179,800,000)	(193,136,000)
Costs in excess of billings	20,063,000	14,894,000
Contracts receivable [Abstract]
Unbilled revenue	21,572,000	15,965,000
Billings in excess of costs incurred and estimated earnings on uncompleted contracts	(824,000)	(1,071,000)
Unbilled contracts receivable	20,748,000	14,894,000
Non-construction activities
Contracts receivable [Abstract]
Unbilled revenue	CAD 685,000	CAD 0

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Billings on Uncompleted Contracts or Programs

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Amount billed to customers under long-term contracts or programs but not paid. Excludes amounts due that have been withheld because of retainage provisions in a contract.

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Liability attributable to (i) billings in excess of costs under the percentage of completion contract accounting method representing the difference between contractually invoiced amounts (billings) and revenue recognized based, for example, on costs incurred to estimated total costs at period end or (ii) contractually invoiced amounts (billings) in excess of costs incurred and accumulated under the completed contract accounting method that are expected to be realized within one year or one operating cycle, whichever is longer, from the reporting date.

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Amount of receivable reflecting the cost incurred on uncompleted contracts in excess of related billings.

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Unbilled amounts due for services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the entity and, at a minimum, one other party. An example would be amounts associated with contracts or programs where the recognized revenue for performance thereunder exceeds the amounts billed under the terms thereof as of the date of the balance sheet.

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