SEGMENT INFORMATION - Summary of Segment Information and Segmented Total Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating Revenues	$ 2,629,342	$ 2,572,641	$ 6,424,985	$ 6,043,951
Depreciation and Amortization	(101,500)	(364,600)	(338,500)	(891,000)
Other Operating Expenses	(1,967,100)	(1,752,400)	(4,776,300)	(4,034,400)
Operating Income	560,662	455,569	1,310,234	1,118,623
Interest Expense	(207,313)	(160,090)	(401,858)	(313,334)
Impairment of Offshore Wind Investment	(401,000)	0	(401,000)	0
Other Income, Net	94,875	93,861	183,857	165,422
Net Income Attributable to Common Shareholders	15,422	291,862	506,581	735,309
Cash Flows Used for Investments in Plant			2,039,512	1,549,081
Assets	54,539,745		54,539,745		$ 53,230,900
Other
Segment Reporting Information [Line Items]
Operating Revenues	408,800	335,700	822,700	719,300
Depreciation and Amortization	(38,000)	(33,200)	(74,800)	(63,400)
Other Operating Expenses	(337,200)	(279,400)	(676,900)	(610,900)
Operating Income	33,600	23,100	71,000	45,000
Interest Expense	(100,600)	(53,500)	(185,700)	(100,300)
Impairment of Offshore Wind Investment	(401,000)		(401,000)
Other Income, Net	100,900	354,300	666,800	850,200
Net Income Attributable to Common Shareholders	(292,400)	316,000	224,700	784,700
Cash Flows Used for Investments in Plant			139,100	122,700
Assets	27,475,000		27,475,000		26,365,200
Eliminations
Segment Reporting Information [Line Items]
Operating Revenues	(781,200)	(695,900)	(1,542,100)	(1,405,700)
Depreciation and Amortization	2,200	1,600	4,300	3,300
Other Operating Expenses	779,500	692,100	1,538,800	1,400,800
Operating Income	500	(2,200)	1,000	(1,600)
Interest Expense	34,400	16,300	66,400	26,400
Impairment of Offshore Wind Investment	0		0
Other Income, Net	(74,600)	(335,400)	(625,300)	(828,500)
Net Income Attributable to Common Shareholders	(39,700)	(321,300)	(557,900)	(803,700)
Cash Flows Used for Investments in Plant			0	0
Assets	(25,829,100)		(25,829,100)		(24,737,500)
Electric Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	2,054,400	2,004,400	4,643,000	4,390,700
Depreciation and Amortization	82,100	(198,100)	60,000	(549,700)
Other Operating Expenses	(1,905,200)	(1,636,100)	(4,247,400)	(3,481,700)
Operating Income	231,300	170,200	455,600	359,300
Interest Expense	(68,200)	(60,300)	(137,600)	(119,800)
Impairment of Offshore Wind Investment	0		0
Other Income, Net	47,900	53,000	102,100	100,500
Net Income Attributable to Common Shareholders	165,500	129,000	331,000	269,900
Cash Flows Used for Investments in Plant			817,300	541,800
Assets	27,932,600		27,932,600		27,365,000
Natural Gas Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	409,100	416,200	1,454,300	1,343,800
Depreciation and Amortization	(41,700)	(39,100)	(118,700)	(91,100)
Other Operating Expenses	(339,400)	(360,700)	(1,069,800)	(1,018,000)
Operating Income	28,000	16,400	265,800	234,700
Interest Expense	(21,500)	(16,700)	(42,700)	(32,500)
Impairment of Offshore Wind Investment	0		0
Other Income, Net	9,700	10,600	18,700	20,800
Net Income Attributable to Common Shareholders	11,700	7,700	181,900	171,700
Cash Flows Used for Investments in Plant			371,500	275,400
Assets	8,089,800		8,089,800		8,084,900
Electric Transmission | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	480,100	457,600	938,800	892,800
Depreciation and Amortization	(92,000)	(83,300)	(181,900)	(165,300)
Other Operating Expenses	(136,200)	(141,300)	(264,500)	(270,500)
Operating Income	251,900	233,000	492,400	457,000
Interest Expense	(42,200)	(37,500)	(83,700)	(70,600)
Impairment of Offshore Wind Investment	0		0
Other Income, Net	9,500	9,300	18,900	18,200
Net Income Attributable to Common Shareholders	161,000	151,500	316,100	300,000
Cash Flows Used for Investments in Plant			636,900	543,600
Assets	14,054,200		14,054,200		13,369,500
Water Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	58,100	54,600	108,300	103,100
Depreciation and Amortization	(14,100)	(12,500)	(27,400)	(24,800)
Other Operating Expenses	(28,600)	(27,000)	(56,500)	(54,100)
Operating Income	15,400	15,100	24,400	24,200
Interest Expense	(9,200)	(8,400)	(18,600)	(16,500)
Impairment of Offshore Wind Investment	0		0
Other Income, Net	1,500	2,100	2,700	4,200
Net Income Attributable to Common Shareholders	9,300	$ 9,000	10,800	12,700
Cash Flows Used for Investments in Plant			74,700	$ 65,600
Assets	$ 2,817,200		$ 2,817,200		$ 2,783,800