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Financial instruments - Long-term Energy Derivative Contracts (Detail) - Cash flow hedge | Dec. 31, 2020 MWh $ / MWh $ / MWh
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PJM Western HUB |
Derivative [Line Items] |
Notional quantity (MW-hrs) | MWh | 642,280
Receive average prices (per MW-hr) | $ / MWh | 34.02
NI HUB, Expiry December 2031 |
Derivative [Line Items] |
Notional quantity (MW-hrs) | MWh | 2,479,234
Receive average prices (per MW-hr) | $ / MWh | 23.50
NI HUB, Expiry December 2027 |
Derivative [Line Items] |
Notional quantity (MW-hrs) | MWh | 2,953,751
Receive average prices (per MW-hr) | $ / MWh | 24.76
ERCOT North HUB |
Derivative [Line Items] |
Notional quantity (MW-hrs) | MWh | 2,330,995
Receive average prices (per MW-hr) | $ / MWh | 36.46

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