NSTAR ELECTRIC COMPANY AND SUBSIDIARY 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	$ (434,700)	$ 1,412,400	$ 1,228,000
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 Contributions	(6,860)	(83,148)	(182,344)
Regulatory Under Recoveries, Net	(151,548)	(205,294)	(314,211)
Cost of Removal Expenditures	(315,699)	(303,755)	(242,130)
Payment in 2022 of Withheld Property Taxes	0	(78,446)	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)
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:
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 To Eversource Parent	695,552	(78,170)	256,125
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
NSTAR Electric
Operating Activities:
Net (Loss)/Income	544,528	492,428	476,569
Adjustments to Reconcile Net (Loss)/Income to Net Cash Flows Provided by Operating Activities:
Depreciation	372,578	361,969	337,451
Deferred Income Taxes	96,224	78,039	57,507
Uncollectible Expense	22,791	21,550	16,649
Pension, SERP and PBOP Income, Net	(41,554)	(55,830)	(26,120)
Pension Contributions	0	(15,000)	(30,000)
Regulatory Under Recoveries, Net	(141,865)	(88,220)	(79,075)
Amortization of Regulatory (Liabilities)/Assets, Net	16,150	83,855	55,774
Cost of Removal Expenditures	(68,290)	(57,339)	(58,967)
Payment in 2022 of Withheld Property Taxes	0	(76,311)	0
Other	(2,123)	(14,294)	(32,447)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(82,659)	(23,757)	(45,774)
Taxes Receivable/Accrued, Net	27,394	35,143	(16,219)
Accounts Payable	11,357	8,815	31,650
Other Current Assets and Liabilities, Net	(40,974)	20,430	13,944
Net Cash Flows Provided by Operating Activities	713,557	771,478	700,942
Investing Activities:
Investments in Property, Plant and Equipment	(1,376,135)	(954,281)	(960,949)
Other Investing Activities	48	165	91
Net Cash Flows Used in Investing Activities	(1,376,087)	(954,116)	(960,858)
Financing Activities:
Cash Dividends on Common Shares	(327,400)	(287,600)	(283,200)
Cash Dividends on Preferred Stock	(1,960)	(1,960)	(1,960)
Increase/(Decrease) in Notes Payable	365,847	(162,500)	(32,500)
Increase (Decrease) in Notes Payable To Eversource Parent	0	0	(21,300)
Capital Contributions from Eversource Parent	234,900	525,000	260,000
Issuance of Long-Term Debt	150,000	850,000	600,000
Retirement of Long-Term Debt	(80,000)	(400,000)	(250,000)
Other Financing Activities	(1,365)	(13,188)	(10,355)
Net Cash Flows Provided by Financing Activities	340,022	509,752	260,685
Net (Decrease)/Increase in Cash, Cash Equivalents and Restricted Cash	(322,508)	327,114	769
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	345,293	18,179	17,410
Cash, Cash Equivalents and Restricted Cash - End of Year	$ 22,785	$ 345,293	$ 18,179