COMMON SHARES - Common Shares Authorized and Issued (Details) - $ / shares |
Jun. 30, 2026 |
Dec. 31, 2025 |
Jun. 30, 2025 |
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| Class of Stock [Line Items] | |||
| Par value (in dollars per share) | $ 5 | $ 5 | $ 5 |
| Authorized (in shares) | 410,000,000 | 410,000,000 | |
| Issued as of (in shares) | 383,143,545 | 382,854,501 | |
| CL&P | |||
| Class of Stock [Line Items] | |||
| Par value (in dollars per share) | $ 10 | $ 10 | |
| Authorized (in shares) | 24,500,000 | 24,500,000 | |
| Issued as of (in shares) | 6,035,205 | 6,035,205 | |
| NSTAR Electric | |||
| Class of Stock [Line Items] | |||
| Par value (in dollars per share) | $ 1 | $ 1 | |
| Authorized (in shares) | 100,000,000 | 100,000,000 | |
| Issued as of (in shares) | 200 | 200 | |
| PSNH | |||
| Class of Stock [Line Items] | |||
| Par value (in dollars per share) | $ 1 | $ 1 | |
| Authorized (in shares) | 100,000,000 | 100,000,000 | |
| Issued as of (in shares) | 301 | 301 |
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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. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Face amount or stated value per share of common stock. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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