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v3.20.2

Derivatives and Risk Management - Additional Information (Details) |  | 1 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jun. 30, 2020 USD ($) Contract | Jul. 31, 2020 USD ($) | Sep. 30, 2020 USD ($) MWh MMBTU | Sep. 30, 2019 USD ($) | Dec. 31, 2019 MWh MMBTU
Derivative [Line Items] |  |  |  |  |
Payments for (proceeds from) derivative instrument operating activities | $ |  |  | $ 33,499,000 | $ 13,325,000 |
Canadian [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Number of days Canadian currency prices are settled with U.S. dollars |  |  | 60 days |  |
Interest Rate Swap [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Number of interest rate swaps settled | Contract | 7 |  |  |  |
Settled derivative notional amount | $ | $ 70,000,000.0 |  |  |  |
Payments for (proceeds from) derivative instrument operating activities | $ |  | $ 33,500,000 |  |  |
Purchase [Member] | Physical [Member] | Electric Derivative [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Expected deliveries of energy commodity derivatives after 2023 | MWh |  |  | 0 |  |
Expected deliveries of energy commodity derivatives after 2022 | MWh |  |  |  |  | 0
Purchase [Member] | Physical [Member] | Gas Derivative [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Expected deliveries of energy commodity derivatives after 2023 | MMBTU |  |  | 0 |  |
Expected deliveries of energy commodity derivatives after 2022 | MMBTU |  |  |  |  | 0
Purchase [Member] | Financial [Member] | Electric Derivative [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Expected deliveries of energy commodity derivatives after 2023 | MWh |  |  | 0 |  |
Expected deliveries of energy commodity derivatives after 2022 | MWh |  |  |  |  | 0
Purchase [Member] | Financial [Member] | Gas Derivative [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Expected deliveries of energy commodity derivatives after 2023 | MMBTU |  |  | 0 |  |
Expected deliveries of energy commodity derivatives after 2022 | MMBTU |  |  |  |  | 0
Sales [Member] | Physical [Member] | Electric Derivative [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Expected deliveries of energy commodity derivatives after 2023 | MWh |  |  | 0 |  |
Expected deliveries of energy commodity derivatives after 2022 | MWh |  |  |  |  | 0
Sales [Member] | Physical [Member] | Gas Derivative [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Expected deliveries of energy commodity derivatives after 2023 | MMBTU |  |  | 0 |  |
Expected deliveries of energy commodity derivatives after 2022 | MMBTU |  |  |  |  | 0
Sales [Member] | Financial [Member] | Electric Derivative [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Expected deliveries of energy commodity derivatives after 2023 | MWh |  |  | 0 |  |
Expected deliveries of energy commodity derivatives after 2022 | MWh |  |  |  |  | 0
Sales [Member] | Financial [Member] | Gas Derivative [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Expected deliveries of energy commodity derivatives after 2023 | MMBTU |  |  | 0 |  |
Expected deliveries of energy commodity derivatives after 2022 | MMBTU |  |  |  |  | 0

X
- Definition Energy commodity derivative expected to be settle after year four. + References No definition available. + Details
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- Definition Energy commodity derivative expected to be settle after year three. + References No definition available. + Details
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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. + References No definition available. + Details
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