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, Net of Cash and Cash Equivalents

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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 Post-employment Benefits

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Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Noncontrolling Interest

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Business Combination, Tax Equity Funding

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Busness Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Derivative Instruments

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Cumulative Ownership Interest Acquired

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Disposal of Partial Interest in Consolidated Entity, Ownership Interest Disposed

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Noncontrolling Interest Disposed, Amount

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Number of Wind Farms

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Partnership Agreement, Funded Amount

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Solar Power Capacity

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Wind Power Capacity

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- Definition

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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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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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 currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of deferred tax liability attributable to taxable temporary differences assumed at the acquisition date.

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Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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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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Gross amount of debt extinguished.

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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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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The amount deducted from an entities' taxes, reflecting a percentage of an amount invested in certain assets spread over the useful life of those assets; includes deferred investment tax credits.

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The proportionate share of interest (percent) in a jointly owned utility plant.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Useful life of other equipment owned by public utility, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Business acquisitions (Details) $ in Thousands, $ in Thousands								1 Months Ended	2 Months Ended	12 Months Ended
	Nov. 09, 2020 USD ($)	Oct. 17, 2020 USD ($)	Oct. 13, 2020 USD ($)	Dec. 31, 2019 USD ($) MWac	Nov. 01, 2019 USD ($)	Oct. 01, 2019 USD ($)	Oct. 01, 2019 CAD ($)	Nov. 30, 2019 windProject	Mar. 04, 2021 USD ($)	Dec. 31, 2020 USD ($) MWac	Dec. 31, 2020 CAD ($) MWac	Dec. 31, 2019 USD ($) windProject MWac	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Goodwill				$ 1,031,696						$ 1,208,390		$ 1,031,696	$ 954,282
Non-controlling interest		$ (84,525)
Number of wind projects \| windProject												3
Turquoise Solar Facility
Business Acquisition [Line Items]
Total purchase price				$ 20,830
Solar power capacity (megawatt ac) \| MWac				10						10	10
Turquoise Solar Facility \| Partnership
Business Acquisition [Line Items]
Partnership agreement, funded amount										$ 3,717		$ 3,403
Great Bay Solar II Facility
Business Acquisition [Line Items]
Solar power capacity (megawatt ac) \| MWac										40	40
Tax equity funding				$ 11,281						$ 15,268		11,281
Investment tax credit										10,717		$ 8,526
North Fork Ridge Wind Project
Business Acquisition [Line Items]
Tax equity funding										$ 29,446
Empire Electric System \| North Fork Ridge Wind Project \| Subsequent Event
Business Acquisition [Line Items]
Total purchase price									$ 288,066
Tax equity funding									84,926
Construction loan repaid									$ 193,506
Ascendant
Business Acquisition [Line Items]
Total purchase price	$ 364,468
Working capital	71,948
Property, plant and equipment	417,947
Intangible assets	27,315
Goodwill	93,202
Regulatory assets	9,859
Other assets	4,992
Long-term debt	(159,682)
Pension and other post-employment benefits	(58,746)
Derivative instruments	(12,748)
Other liabilities	(29,619)
Total net assets acquired	364,468
Cash and cash equivalents acquired	42,920
Total net assets acquired, net of cash and cash equivalents	$ 321,548
Weighted average useful life of assets	29 years
ESSAL
Business Acquisition [Line Items]
Total purchase price		$ 74,111	$ 87,975
Ownership interest acquired (percent)		43.00%	51.00%
Cumulative ownership interest acquired (percent)		94.00%
Working capital		$ 11,278
Property, plant and equipment		238,504
Intangible assets		37,095
Goodwill		70,382
Other assets		22
Long-term debt		(139,534)
Pension and other post-employment benefits		(2,292)
Deferred tax liabilities, net		(28,074)
Other liabilities		(14,881)
Total net assets acquired		87,975
Cash and cash equivalents acquired		6,983
Total net assets acquired, net of cash and cash equivalents		$ 80,992
Weighted average useful life of assets		40 years
ESSAL \| Subsequent Event
Business Acquisition [Line Items]
Ownership interest sold (percent)									32.00%
Ownership interest after transaction (percent)									64.00%
ESSAL \| APUC
Business Acquisition [Line Items]
Non-controlling interest (percent)										6.00%
ESSAL \| Third Party \| Subsequent Event
Business Acquisition [Line Items]
Ownership interest sold									$ 51,750
New Brunswick Gas
Business Acquisition [Line Items]
Total purchase price						$ 256,011	$ 339,036
Increase (decrease) in goodwill										$ (1,213)	$ (1,884)
St. Lawrence Gas Company, Inc.
Business Acquisition [Line Items]
Total purchase price					$ 61,820
Increase (decrease) in goodwill										$ 3,207
Mid-west Wind Development Project
Business Acquisition [Line Items]
Wind power capacity (megawatt AC) \| MWac												600
Southwestern Missouri Wind Projects
Business Acquisition [Line Items]
Number of wind projects \| windProject								2