SEGMENT INFORMATION - Schedule of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating Revenues			$ 11,910,705	$ 12,289,336	$ 9,863,085
Depreciation and Amortization			(815,700)	(1,643,100)	(1,335,000)
Other Operating Expenses			(8,695,700)	(8,448,000)	(6,534,800)
Operating Income			2,399,335	2,198,154	1,993,321
Interest Expense			(855,441)	(678,274)	(582,334)
Impairments of Offshore Wind Investments	$ (1,766,000)	$ (401,000)	(2,167,000)	0	0
Interest Income			94,200	50,500	25,600
Other Income, Net			253,900	295,600	135,700
Income Tax (Expense)/Benefit			(159,684)	(453,574)	(344,223)
Net (Loss)/Income			(434,700)	1,412,400	1,228,000
Net Income Attributable to Noncontrolling Interests			(7,519)	(7,519)	(7,519)
Net Income Attributable to Common Shareholders			(442,240)	1,404,875	1,220,527
Total Assets (as of)	55,612,245		55,612,245	53,230,900
Cash Flows Used for Investments in Plant			4,336,800	3,441,900	3,175,100
Operating Segments | Electric Distribution
Segment Reporting Information [Line Items]
Operating Revenues			8,973,500	9,405,300	7,423,600
Depreciation and Amortization			(18,200)	(970,400)	(737,800)
Other Operating Expenses			(8,104,600)	(7,663,700)	(5,970,000)
Operating Income			850,700	771,200	715,800
Interest Expense			(291,700)	(253,100)	(236,400)
Impairments of Offshore Wind Investments			0
Interest Income			74,500	45,100	20,700
Other Income, Net			136,200	180,400	78,100
Income Tax (Expense)/Benefit			(157,100)	(146,200)	(103,500)
Net (Loss)/Income			612,600	597,400	474,700
Net Income Attributable to Noncontrolling Interests			(4,600)	(4,600)	(4,600)
Net Income Attributable to Common Shareholders			608,000	592,800	470,100
Total Assets (as of)	29,426,400		29,426,400	27,365,000
Cash Flows Used for Investments in Plant			1,668,100	1,172,600	1,053,300
Operating Segments | Natural Gas Distribution
Segment Reporting Information [Line Items]
Operating Revenues			2,221,700	2,215,600	1,789,600
Depreciation and Amortization			(214,200)	(157,600)	(142,300)
Other Operating Expenses			(1,662,600)	(1,727,000)	(1,345,400)
Operating Income			344,900	331,000	301,900
Interest Expense			(85,700)	(71,400)	(58,600)
Impairments of Offshore Wind Investments			0
Interest Income			18,200	10,200	4,500
Other Income, Net			20,400	33,600	17,900
Income Tax (Expense)/Benefit			(73,000)	(69,200)	(60,900)
Net (Loss)/Income			224,800	234,200	204,800
Net Income Attributable to Noncontrolling Interests			0	0	0
Net Income Attributable to Common Shareholders			224,800	234,200	204,800
Total Assets (as of)	8,775,300		8,775,300	8,084,900
Cash Flows Used for Investments in Plant			844,100	710,300	721,100
Operating Segments | Electric Transmission
Segment Reporting Information [Line Items]
Operating Revenues			1,915,900	1,808,700	1,634,600
Depreciation and Amortization			(371,200)	(337,400)	(300,300)
Other Operating Expenses			(550,500)	(548,400)	(496,200)
Operating Income			994,200	922,900	838,100
Interest Expense			(163,700)	(145,500)	(133,200)
Impairments of Offshore Wind Investments			0
Interest Income			400	500	2,200
Other Income, Net			41,200	37,900	19,800
Income Tax (Expense)/Benefit			(225,800)	(216,300)	(179,400)
Net (Loss)/Income			646,300	599,500	547,500
Net Income Attributable to Noncontrolling Interests			(2,900)	(2,900)	(2,900)
Net Income Attributable to Common Shareholders			643,400	596,600	544,600
Total Assets (as of)	14,806,500		14,806,500	13,369,500
Cash Flows Used for Investments in Plant			1,406,300	1,144,000	1,024,100
Operating Segments | Water Distribution
Segment Reporting Information [Line Items]
Operating Revenues			232,500	222,500	211,300
Depreciation and Amortization			(56,000)	(50,900)	(46,100)
Other Operating Expenses			(117,100)	(111,800)	(101,400)
Operating Income			59,400	59,800	63,800
Interest Expense			(38,500)	(34,700)	(32,000)
Impairments of Offshore Wind Investments			0
Interest Income			0	0	0
Other Income, Net			5,900	8,500	3,300
Income Tax (Expense)/Benefit			6,300	3,200	1,700
Net (Loss)/Income			33,100	36,800	36,800
Net Income Attributable to Noncontrolling Interests			0	0	0
Net Income Attributable to Common Shareholders			33,100	36,800	36,800
Total Assets (as of)	2,944,800		2,944,800	2,783,800
Cash Flows Used for Investments in Plant			167,000	154,400	137,200
Other
Segment Reporting Information [Line Items]
Operating Revenues			1,636,600	1,435,500	1,354,000
Depreciation and Amortization			(158,800)	(132,600)	(113,100)
Other Operating Expenses			(1,329,800)	(1,189,100)	(1,170,400)
Operating Income			148,000	113,800	70,500
Interest Expense			(425,300)	(247,800)	(168,800)
Impairments of Offshore Wind Investments			(2,167,000)
Interest Income			150,600	66,300	46,000
Other Income, Net			(261,800)	1,600,800	1,363,900
Income Tax (Expense)/Benefit			289,900	(25,100)	(2,100)
Net (Loss)/Income			(2,265,600)	1,508,000	1,309,500
Net Income Attributable to Noncontrolling Interests			0	0	0
Net Income Attributable to Common Shareholders			(2,265,600)	1,508,000	1,309,500
Total Assets (as of)	26,337,700		26,337,700	26,365,200
Cash Flows Used for Investments in Plant			251,300	260,600	239,400
Eliminations
Segment Reporting Information [Line Items]
Operating Revenues			(3,069,500)	(2,798,300)	(2,550,000)
Depreciation and Amortization			2,700	5,800	4,600
Other Operating Expenses			3,068,900	2,792,000	2,548,600
Operating Income			2,100	(500)	3,200
Interest Expense			149,500	74,200	46,600
Impairments of Offshore Wind Investments			0
Interest Income			(149,500)	(71,600)	(47,800)
Other Income, Net			312,000	(1,565,600)	(1,347,300)
Income Tax (Expense)/Benefit			0	0	0
Net (Loss)/Income			314,100	(1,563,500)	(1,345,300)
Net Income Attributable to Noncontrolling Interests			0	0	0
Net Income Attributable to Common Shareholders			314,100	(1,563,500)	(1,345,300)
Total Assets (as of)	$ (26,678,500)		(26,678,500)	(24,737,500)
Cash Flows Used for Investments in Plant			$ 0	$ 0	$ 0