v3.26.1
SEGMENT INFORMATION - Segment Information and Segmented Total Assets (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Segment Reporting [Line Items]              
Operating Revenues $ 2,903,189   $ 2,838,068   $ 7,407,552 $ 6,956,423  
Depreciation and Amortization (379,600)   (494,700)   (1,202,800) (1,329,800)  
Total Operations and Maintenance (480,441)   (467,557)   (987,420) (955,008)  
Purchased Power, Purchased Natural Gas and Transmission, Other Taxes and Energy Efficiency (1,390,900)   (1,212,800)   (3,489,000) (3,082,200)  
Sale of Aquarion (111,360)   0   (111,360) 0  
Operating Income 540,874   663,049   1,617,022 1,589,443  
Interest Expense (355,400)            
Interest Expense (355,490)   (293,193)   (720,749) (594,042)  
Loss on Offshore Wind (194,000)   0   (194,000) 0  
Interest Income 32,600   30,800   61,000 64,800  
Other Income, Net 111,400   64,600   184,200 122,900  
Income Tax (Expense)/Benefit (79,857)   (110,611)   (283,184) (275,831)  
Net Income 55,560 $ 608,721 354,608 $ 552,668 664,281 907,276  
Net Income Attributable to Noncontrolling Interests (1,880)   (1,880)   (3,759) (3,759)  
Net Income Attributable to Common Shareholders 53,680   352,728   660,522 903,517  
Cash Flows Used for Investments in Plant         2,023,500 2,049,400  
Assets 63,415,743       63,415,743   $ 63,786,711
Other              
Segment Reporting [Line Items]              
Operating Revenues 439,800   405,800   924,300 844,900  
Depreciation and Amortization (60,900)   (53,400)   (121,500) (104,100)  
Total Operations and Maintenance (346,200)   (313,300)   (737,900) (662,400)  
Purchased Power, Purchased Natural Gas and Transmission, Other Taxes and Energy Efficiency 1,100   (1,000)   300 (2,400)  
Sale of Aquarion 0       0    
Operating Income 33,800   38,100   65,200 76,000  
Interest Expense (188,400)            
Interest Expense     (176,900)   (368,600) (355,300)  
Loss on Offshore Wind (194,000)       (194,000)    
Interest Income 38,300   43,200   77,500 86,600  
Other Income, Net 135,400   433,900   827,500 1,059,600  
Income Tax (Expense)/Benefit 38,300   23,700   64,800 57,100  
Net Income (136,600)   362,000   472,400 924,000  
Net Income Attributable to Noncontrolling Interests 0   0   0 0  
Net Income Attributable to Common Shareholders (136,600)   362,000   472,400 924,000  
Cash Flows Used for Investments in Plant         134,900 119,900  
Assets 29,851,400       29,851,400   29,743,300
Eliminations              
Segment Reporting [Line Items]              
Operating Revenues (892,200)   (824,700)   (1,824,200) (1,662,500)  
Depreciation and Amortization 3,900   3,600   8,100 6,300  
Total Operations and Maintenance 447,500   409,700   938,600 850,700  
Purchased Power, Purchased Natural Gas and Transmission, Other Taxes and Energy Efficiency 440,800   411,400   877,500 805,500  
Sale of Aquarion 0       0    
Operating Income 0   0   0 0  
Interest Expense 38,300            
Interest Expense     43,200   77,500 86,600  
Loss on Offshore Wind 0       0    
Interest Income (38,300)   (43,200)   (77,500) (86,600)  
Other Income, Net (93,700)   (428,500)   (780,700) (1,049,600)  
Income Tax (Expense)/Benefit 0   0   0 0  
Net Income (93,700)   (428,500)   (780,700) (1,049,600)  
Net Income Attributable to Noncontrolling Interests 0   0   0 0  
Net Income Attributable to Common Shareholders (93,700)   (428,500)   (780,700) (1,049,600)  
Cash Flows Used for Investments in Plant         0 0  
Assets (30,159,400)       (30,159,400)   (31,851,700)
Electric Distribution | Operating Segments              
Segment Reporting [Line Items]              
Operating Revenues 2,183,500   2,166,400   5,124,000 4,944,100  
Depreciation and Amortization (98,400)   (265,800)   (640,100) (830,600)  
Operations, Excluding Storm Costs (95,500)   (96,500)   (202,400) (198,100)  
Corporate Shared Services (121,100)   (105,700)   (242,700) (222,000)  
Storm Costs (11,500)   (21,900)   (40,400) (41,800)  
Employee Benefits (42,900)   (47,300)   (82,000) (95,800)  
Uncollectible Expense (37,400)   (41,100)   (73,000) (84,800)  
Other (51,700)   (39,600)   (83,000) (67,300)  
Total Operations and Maintenance (360,100)   (352,100)   (723,500) (709,800)  
Purchased Power, Purchased Natural Gas and Transmission, Other Taxes and Energy Efficiency (1,463,300)   (1,307,900)   (3,198,400) (2,888,400)  
Sale of Aquarion 0       0    
Operating Income 261,700   240,600   562,000 515,300  
Interest Expense (107,600)            
Interest Expense     (95,400)   (207,700) (186,500)  
Loss on Offshore Wind 0       0    
Interest Income 22,500   24,800   43,000 52,100  
Other Income, Net 44,700   39,300   89,700 74,600  
Income Tax (Expense)/Benefit (49,700)   (46,600)   (111,600) (103,200)  
Net Income 171,600   162,700   375,400 352,300  
Net Income Attributable to Noncontrolling Interests (1,200)   (1,200)   (2,300) (2,300)  
Net Income Attributable to Common Shareholders 170,400   161,500   373,100 350,000  
Cash Flows Used for Investments in Plant         951,400 983,200  
Assets 35,435,500       35,435,500   34,858,100
Natural Gas Distribution | Operating Segments              
Segment Reporting [Line Items]              
Operating Revenues 528,700   460,800   1,901,800 1,602,100  
Depreciation and Amortization (85,200)   (57,700)   (182,700) (162,100)  
Operations, Excluding Storm Costs (33,900)   (40,800)   (84,500) (87,100)  
Corporate Shared Services (29,900)   (28,000)   (60,300) (58,300)  
Storm Costs 0   0   0 0  
Employee Benefits (17,700)   (17,200)   (38,500) (35,700)  
Uncollectible Expense (18,400)   (13,400)   (51,900) (43,400)  
Other (6,000)   (5,100)   (6,500) (2,900)  
Total Operations and Maintenance (105,900)   (104,500)   (241,700) (227,400)  
Purchased Power, Purchased Natural Gas and Transmission, Other Taxes and Energy Efficiency (282,100)   (235,400)   (999,900) (840,700)  
Sale of Aquarion 0       0    
Operating Income 55,500   63,200   477,500 371,900  
Interest Expense (34,800)            
Interest Expense     (28,100)   (68,800) (56,500)  
Loss on Offshore Wind 0       0    
Interest Income 9,900   5,800   17,700 12,400  
Other Income, Net 10,000   8,900   16,800 14,500  
Income Tax (Expense)/Benefit (10,900)   (14,500)   (118,100) (88,600)  
Net Income 29,700   35,300   325,100 253,700  
Net Income Attributable to Noncontrolling Interests 0   0   0 0  
Net Income Attributable to Common Shareholders 29,700   35,300   325,100 253,700  
Cash Flows Used for Investments in Plant         333,900 372,500  
Assets 10,725,600       10,725,600   10,865,500
Electric Transmission | Operating Segments              
Segment Reporting [Line Items]              
Operating Revenues 581,000   568,700   1,165,700 1,116,500  
Depreciation and Amortization (125,100)   (109,600)   (240,400) (216,300)  
Operations, Excluding Storm Costs (37,900)   (37,000)   (72,500) (68,500)  
Corporate Shared Services (20,500)   (16,900)   (42,200) (38,700)  
Storm Costs 0   0   0 0  
Employee Benefits (12,600)   (11,900)   (24,300) (23,600)  
Uncollectible Expense 0   0   0 0  
Other (19,300)   (18,300)   (35,800) (29,200)  
Total Operations and Maintenance (90,300)   (84,100)   (174,800) (160,000)  
Purchased Power, Purchased Natural Gas and Transmission, Other Taxes and Energy Efficiency (80,800)   (73,200)   (154,800) (142,800)  
Sale of Aquarion 0       0    
Operating Income 284,800   301,800   595,700 597,400  
Interest Expense (55,600)            
Interest Expense     (28,300)   (138,600) (66,800)  
Loss on Offshore Wind 0       0    
Interest Income 200   200   300 300  
Other Income, Net 14,200   9,600   28,400 21,600  
Income Tax (Expense)/Benefit (59,200)   (74,600)   (120,200) (143,500)  
Net Income 184,400   208,700   365,600 409,000  
Net Income Attributable to Noncontrolling Interests (700)   (700)   (1,500) (1,500)  
Net Income Attributable to Common Shareholders 183,700   208,000   364,100 407,500  
Cash Flows Used for Investments in Plant         531,300 505,700  
Assets 17,562,600       17,562,600   17,193,900
Water Distribution | Operating Segments              
Segment Reporting [Line Items]              
Operating Revenues 62,400   61,100   116,000 111,300  
Depreciation and Amortization (13,900)   (11,800)   (26,200) (23,000)  
Total Operations and Maintenance (25,400)   (23,300)   (48,100) (46,100)  
Purchased Power, Purchased Natural Gas and Transmission, Other Taxes and Energy Efficiency (6,600)   (6,700)   (13,700) (13,400)  
Sale of Aquarion (111,400)       (111,400)    
Operating Income (94,900)   19,300   (83,400) 28,800  
Interest Expense (7,300)            
Interest Expense     (7,700)   (14,500) (15,500)  
Loss on Offshore Wind 0       0    
Interest Income 0   0   0 0  
Other Income, Net 800   1,400   2,500 2,200  
Income Tax (Expense)/Benefit 1,600   1,400   1,900 2,400  
Net Income (99,800)   14,400   (93,500) 17,900  
Net Income Attributable to Noncontrolling Interests 0   0   0 0  
Net Income Attributable to Common Shareholders (99,800)   $ 14,400   (93,500) 17,900  
Cash Flows Used for Investments in Plant         72,000 $ 68,100  
Assets $ 0       $ 0   $ 2,977,600