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COMMITMENTS AND CONTINGENCIES - Non-Cancellable Commitments under Purchase Commitment Contracts (Details) - Renewable Energy - NSTAR Electric $ in Millions | 9 Months Ended
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Sep. 30, 2021 USD ($)
Unrecorded Unconditional Purchase Obligation [Line Items] |
2021 | $ 27.1
2022 | 103.9
2023 | 230.5
2024 | 341.2
2025 | 348.1
Thereafter | 6,564.2
Total | 7,615.0
Massachusetts Clean Energy 83D Contract |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Total | $ 6,700.0
Contract term | 20 years
Minimum | Massachusetts Clean Energy 83D Contract |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Estimated costs | $ 150.0
Maximum | Massachusetts Clean Energy 83D Contract |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Estimated costs | $ 415.0

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- Definition Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308 + Details
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- Definition Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308 + Details
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- Definition Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308 + Details
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- Definition Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308 + Details
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- Definition Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308 + Details
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- Definition Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308 + Details
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- Definition Term of the unrecognized unconditional purchase obligation, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308 + Details
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