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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Working Capital

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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets , Notes Receivable

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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets, Regulatory Assets

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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Pension and Other Postemployment Benefits

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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Regulatory Liabilities

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of liabilities incurred by the acquirer as part of consideration transferred in a business combination.

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This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

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This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

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Amount of deferred tax liability attributable to taxable temporary difference assumed at the acquisition date that are classified as noncurrent.

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Amount of long-term debt due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Business acquisitions and development projects - Acquisition of Park Water System (Details) CAD in Thousands, $ in Thousands			12 Months Ended
	Jan. 08, 2016 CAD water_utility	Jan. 08, 2016 USD ($) water_utility	Dec. 31, 2017 CAD	Dec. 31, 2016 CAD	Dec. 31, 2015 CAD
Business Acquisition [Line Items]
Goodwill (note 6)			CAD 1,196,234	CAD 306,641	CAD 110,493
Park Water Company
Business Acquisition [Line Items]
Working capital	CAD 2,045
Property, plant and equipment	345,254
Notes receivable	1,781
Goodwill (note 6)	210,463
Regulatory assets	54,548
Other assets	185
Long-term debt	(146,727)
Regulatory liabilities	(3,758)
Pension and OPEB	(18,747)
Deferred income tax liability, net	(51,795)
Other liabilities	(40,172)
Total net assets acquired	CAD 353,077
Number of regulated water utilities \| water_utility	3	3
Business combination, purchase price	CAD 353,077	$ 249,540
Business combination, liabilities incurred \| $		$ 91,750
Revenue			91,817	96,695
Pre-tax net earnings			CAD 17,620	CAD 25,374
Weighted Average \| Park Water Company
Business Acquisition [Line Items]
Estimated useful lives	40 years	40 years