CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net (Loss)/Income	$ (434,721)	$ 1,412,394	$ 1,228,046
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	1,305,840	1,194,246	1,103,008
Deferred Income Taxes	85,405	346,779	347,056
Uncollectible Expense	72,468	61,876	60,886
Pension, SERP and PBOP Income, Net	(90,706)	(160,857)	(14,693)
Pension and PBOP Contributions	(6,860)	(83,148)	(182,344)
Regulatory Under Recoveries, Net	(151,548)	(205,294)	(314,211)
(Customer Credits)/Reserve at CL&P related to PURA Settlement Agreement and Storm Performance Penalty	0	(72,041)	81,274
Amortization	(490,117)	448,892	231,965
Cost of Removal Expenditures	(315,699)	(303,755)	(242,130)
Payment in 2022 of Withheld Property Taxes	0	(78,446)	0
Impairments of Offshore Wind Investments	2,167,000	0	0
Other	(53,026)	(39,192)	(64,640)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(124,393)	(470,593)	(135,505)
Taxes Receivable/Accrued, Net	36,357	18,358	(110,621)
Accounts Payable	(287,637)	377,657	(29,201)
Other Current Assets and Liabilities, Net	(66,202)	(45,583)	3,710
Net Cash Flows Provided by Operating Activities	1,646,161	2,401,293	1,962,600
Investing Activities:
Investments in Property, Plant and Equipment	(4,336,849)	(3,441,852)	(3,175,080)
Proceeds from Sales of Marketable Securities	395,604	457,612	447,893
Purchases of Marketable Securities	(336,779)	(424,174)	(414,980)
Investments in Unconsolidated Affiliates	(1,680,473)	(742,496)	(327,385)
Proceeds from Unconsolidated Affiliates	1,090,662	0	0
Other Investing Activities	(2,897)	20,420	22,178
Net Cash Flows Used in Investing Activities	(4,870,732)	(4,130,490)	(3,447,374)
Financing Activities:
Issuance of Common Shares, Net of Issuance Costs	0	197,058	0
Cash Dividends on Common Shares	(918,995)	(860,033)	(805,439)
Cash Dividends on Preferred Stock	(7,519)	(7,519)	(7,519)
Increase/(Decrease) in Notes Payable	695,552	(78,170)	256,125
Repayment of Rate Reduction Bonds	(43,210)	(43,210)	(43,210)
Issuance of Long-Term Debt	5,198,345	4,045,000	3,230,000
Retirement of Long-Term Debt	(2,008,470)	(1,175,000)	(1,142,500)
Other Financing Activities	(46,466)	(48,185)	(46,625)
Net Cash Flows Provided by Financing Activities	2,869,237	2,029,941	1,440,832
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(355,334)	300,744	(43,942)
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	521,752	221,008	264,950
Cash, Cash Equivalents and Restricted Cash - End of Year	$ 166,418	$ 521,752	$ 221,008