v3.26.1
REVENUES (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers $ 2,981,400 $ 2,827,800 $ 7,519,400 $ 6,934,300
Alternative Revenue Programs (84,800) 6,400 (125,400) 10,900
Other Revenues 6,600 3,900 13,600 11,200
Total Operating Revenues 2,903,189 2,838,068 7,407,552 6,956,423
CL&P        
Disaggregation of Revenue [Line Items]        
Total Operating Revenues 1,049,624 1,132,168 2,617,750 2,673,357
NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Total Operating Revenues 937,889 868,925 2,068,977 1,883,152
PSNH        
Disaggregation of Revenue [Line Items]        
Total Operating Revenues 333,940 303,133 717,457 651,114
Total Retail Tariff Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 2,550,900 2,436,800 6,308,200 5,947,900
Residential        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,433,100 1,379,000 3,778,300 3,596,200
Commercial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 965,600 913,000 2,201,800 2,039,900
Industrial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 152,200 144,800 328,100 311,800
Wholesale Transmission Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 157,800 156,800 323,700 311,500
Wholesale Market Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 245,900 205,200 827,600 616,300
Other Revenues from Contracts with Customers        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 26,800 29,000 59,900 58,600
Operating Segments | CL&P        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,248,800 1,307,400 3,032,900 3,040,900
Alternative Revenue Programs (8,600) 3,200 (41,100) (15,700)
Other Revenues 2,100 100 4,400 2,800
Operating Segments | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,149,700 1,061,400 2,483,200 2,262,100
Alternative Revenue Programs (29,900) (7,900) (46,200) (17,000)
Other Revenues 2,200 2,200 4,600 4,600
Operating Segments | PSNH        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 410,700 388,100 877,900 822,200
Alternative Revenue Programs (10,500) (18,800) (26,000) (38,500)
Other Revenues 900 600 2,100 1,500
Operating Segments | Total Retail Tariff Sales Revenues | CL&P        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 848,500 937,000 1,979,700 2,130,800
Operating Segments | Total Retail Tariff Sales Revenues | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 827,700 790,600 1,768,000 1,703,300
Operating Segments | Total Retail Tariff Sales Revenues | PSNH        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 274,300 251,700 601,900 546,800
Operating Segments | Residential | CL&P        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 538,900 583,500 1,326,700 1,384,800
Operating Segments | Residential | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 371,900 379,600 843,000 885,700
Operating Segments | Residential | PSNH        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 160,400 141,100 369,200 323,100
Operating Segments | Commercial | CL&P        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 273,800 309,500 578,200 653,600
Operating Segments | Commercial | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 417,300 377,800 851,800 753,500
Operating Segments | Commercial | PSNH        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 88,300 85,100 183,000 173,400
Operating Segments | Industrial | CL&P        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 35,800 44,000 74,800 92,400
Operating Segments | Industrial | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 38,500 33,200 73,200 64,100
Operating Segments | Industrial | PSNH        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 25,600 25,500 49,700 50,300
Operating Segments | Wholesale Transmission Revenues | CL&P        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 260,600 247,100 529,800 498,200
Operating Segments | Wholesale Transmission Revenues | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 228,400 226,400 464,800 445,100
Operating Segments | Wholesale Transmission Revenues | PSNH        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 121,800 122,900 248,500 247,100
Operating Segments | Wholesale Market Sales Revenues | CL&P        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 131,600 114,700 500,200 394,700
Operating Segments | Wholesale Market Sales Revenues | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 78,800 32,100 222,200 89,400
Operating Segments | Wholesale Market Sales Revenues | PSNH        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 9,500 8,400 18,700 18,800
Operating Segments | Other Revenues from Contracts with Customers | CL&P        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 8,100 8,600 23,200 17,200
Operating Segments | Other Revenues from Contracts with Customers | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 14,800 12,300 28,200 24,300
Operating Segments | Other Revenues from Contracts with Customers | PSNH        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 5,100 5,100 8,800 9,500
Other        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 439,800 405,800 924,300 844,900
Alternative Revenue Programs 0 0 0 0
Other Revenues 0 0 0 0
Total Operating Revenues 439,800 405,800 924,300 844,900
Other | Total Retail Tariff Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Other | Residential        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Other | Commercial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Other | Industrial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Other | Wholesale Transmission Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Other | Wholesale Market Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Other | Other Revenues from Contracts with Customers        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 439,800 405,800 924,300 844,900
Eliminations        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers (906,000) (852,900) (1,867,700) (1,735,900)
Alternative Revenue Programs 13,800 28,200 43,500 73,400
Other Revenues 0 0 0 0
Total Operating Revenues (892,200) (824,700) (1,824,200) (1,662,500)
Eliminations | Total Retail Tariff Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers (10,100) (8,700) (20,200) (16,600)
Eliminations | Residential        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Eliminations | Commercial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers (3,100) (1,900) (6,600) (4,000)
Eliminations | Industrial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers (7,000) (6,800) (13,600) (12,600)
Eliminations | Wholesale Transmission Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers (453,000) (439,600) (919,400) (878,900)
Eliminations | Wholesale Market Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Eliminations | Other Revenues from Contracts with Customers        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers (442,900) (404,600) (928,100) (840,400)
Consolidations Eliminations | CL&P        
Disaggregation of Revenue [Line Items]        
Total Operating Revenues (192,700) (178,500) (378,400) (354,600)
Consolidations Eliminations | NSTAR Electric        
Disaggregation of Revenue [Line Items]        
Total Operating Revenues (184,100) (186,800) (372,600) (366,500)
Consolidations Eliminations | PSNH        
Disaggregation of Revenue [Line Items]        
Total Operating Revenues (67,200) (66,800) (136,500) (134,100)
Electric Distribution | Operating Segments        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 2,194,400 2,156,000 5,134,600 4,925,600
Alternative Revenue Programs (16,100) 7,600 (21,500) 9,800
Other Revenues 5,200 2,800 10,900 8,700
Total Operating Revenues 2,183,500 2,166,400 5,124,000 4,944,100
Electric Distribution | Operating Segments | Total Retail Tariff Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,950,000 1,978,600 4,348,600 4,379,700
Electric Distribution | Operating Segments | Residential        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,071,200 1,104,200 2,538,900 2,593,600
Electric Distribution | Operating Segments | Commercial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 778,900 771,700 1,612,000 1,579,300
Electric Distribution | Operating Segments | Industrial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 99,900 102,700 197,700 206,800
Electric Distribution | Operating Segments | Wholesale Transmission Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Electric Distribution | Operating Segments | Wholesale Market Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 219,900 155,200 741,100 502,900
Electric Distribution | Operating Segments | Other Revenues from Contracts with Customers        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 24,500 22,200 44,900 43,000
Natural Gas Distribution | Operating Segments        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 572,800 457,800 1,952,500 1,591,800
Alternative Revenue Programs (45,200) 2,300 (52,800) 8,600
Other Revenues 1,100 700 2,100 1,700
Total Operating Revenues 528,700 460,800 1,901,800 1,602,100
Natural Gas Distribution | Operating Segments | Total Retail Tariff Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 546,300 407,300 1,865,000 1,477,600
Natural Gas Distribution | Operating Segments | Residential        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 317,300 234,100 1,162,000 930,600
Natural Gas Distribution | Operating Segments | Commercial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 170,900 125,500 561,300 431,500
Natural Gas Distribution | Operating Segments | Industrial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 58,100 47,700 141,700 115,500
Natural Gas Distribution | Operating Segments | Wholesale Transmission Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Natural Gas Distribution | Operating Segments | Wholesale Market Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 24,800 48,900 84,200 111,300
Natural Gas Distribution | Operating Segments | Other Revenues from Contracts with Customers        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,700 1,600 3,300 2,900
Electric Transmission | Operating Segments        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 613,900 599,700 1,257,300 1,197,300
Alternative Revenue Programs (32,900) (31,100) (91,800) (81,000)
Other Revenues 0 100 200 200
Total Operating Revenues 581,000 568,700 1,165,700 1,116,500
Electric Transmission | Operating Segments | Total Retail Tariff Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Electric Transmission | Operating Segments | Residential        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Electric Transmission | Operating Segments | Commercial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Electric Transmission | Operating Segments | Industrial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Electric Transmission | Operating Segments | Wholesale Transmission Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 610,800 596,400 1,243,100 1,190,400
Electric Transmission | Operating Segments | Wholesale Market Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Electric Transmission | Operating Segments | Other Revenues from Contracts with Customers        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 3,100 3,300 14,200 6,900
Water Distribution | Operating Segments        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 66,500 61,400 118,400 110,600
Alternative Revenue Programs (4,400) (600) (2,800) 100
Other Revenues 300 300 400 600
Total Operating Revenues 62,400 61,100 116,000 111,300
Water Distribution | Operating Segments | Total Retail Tariff Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 64,700 59,600 114,800 107,200
Water Distribution | Operating Segments | Residential        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 44,600 40,700 77,400 72,000
Water Distribution | Operating Segments | Commercial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 18,900 17,700 35,100 33,100
Water Distribution | Operating Segments | Industrial        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,200 1,200 2,300 2,100
Water Distribution | Operating Segments | Wholesale Transmission Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 0 0 0 0
Water Distribution | Operating Segments | Wholesale Market Sales Revenues        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers 1,200 1,100 2,300 2,100
Water Distribution | Operating Segments | Other Revenues from Contracts with Customers        
Disaggregation of Revenue [Line Items]        
Revenues from Contracts with Customers $ 600 $ 700 $ 1,300 $ 1,300