NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONDENSED CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital Surplus, Paid In	Retained Earnings	Accumulated Other Comprehensive Loss	NSTAR Electric	NSTAR Electric Common Stock	NSTAR Electric Capital Surplus, Paid In	NSTAR Electric Retained Earnings	NSTAR Electric Accumulated Other Comprehensive Loss
Balance (in shares) at Dec. 31, 2021		344,403,196					200
Balance at Dec. 31, 2021	$ 14,599,844	$ 1,789,092	$ 8,098,514	$ 5,005,391	$ (42,275)	$ 4,973,019	$ 0	$ 2,253,942	$ 2,718,576	$ 501
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	445,326			445,326		92,739			92,739
Dividends on Preferred Stock	(1,880)			(1,880)		(490)			(490)
Dividends on Common Stock	(219,768)			(219,768)		(71,900)			(71,900)
Other Comprehensive Income (Loss)	704				704	(47)				(47)
Balance (in shares) at Mar. 31, 2022		344,850,272					200
Balance at Mar. 31, 2022	14,836,690	$ 1,789,092	8,102,618	5,229,069	(41,571)	4,993,321	$ 0	2,253,942	2,738,925	454
Balance (in shares) at Dec. 31, 2021		344,403,196					200
Balance at Dec. 31, 2021	14,599,844	$ 1,789,092	8,098,514	5,005,391	(42,275)	4,973,019	$ 0	2,253,942	2,718,576	501
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	739,068					212,177
Other Comprehensive Income (Loss)	(589)					(74)
Balance (in shares) at Jun. 30, 2022		346,411,029					200
Balance at Jun. 30, 2022	15,057,215	$ 1,796,056	8,242,346	5,301,054	(42,864)	5,090,341	$ 0	2,303,942	2,785,972	427
Balance (in shares) at Mar. 31, 2022		344,850,272					200
Balance at Mar. 31, 2022	14,836,690	$ 1,789,092	8,102,618	5,229,069	(41,571)	4,993,321	$ 0	2,253,942	2,738,925	454
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	293,742			293,742		119,437			119,437
Dividends on Preferred Stock	(1,880)			(1,880)		(490)			(490)
Dividends on Common Stock	(219,877)			(219,877)		(71,900)			(71,900)
Capital Contributions from Eversource Parent						50,000		50,000
Other Comprehensive Income (Loss)	(1,293)				(1,293)	(27)				(27)
Balance (in shares) at Jun. 30, 2022		346,411,029					200
Balance at Jun. 30, 2022	$ 15,057,215	$ 1,796,056	8,242,346	5,301,054	(42,864)	5,090,341	$ 0	2,303,942	2,785,972	427
Balance (in shares) at Dec. 31, 2022	348,443,855	348,443,855					200
Balance at Dec. 31, 2022	$ 15,473,158	$ 1,799,920	8,401,731	5,527,153	(39,421)	5,700,670	$ 0	2,778,942	2,921,444	284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	493,039			493,039		133,813			133,813
Dividends on Preferred Stock	(1,880)			(1,880)		(490)			(490)
Dividends on Common Stock	(235,354)			(235,354)		(327,400)			(327,400)
Capital Contributions from Eversource Parent						31,300		31,300
Other Comprehensive Income (Loss)	3,230				3,230	(16)				(16)
Balance (in shares) at Mar. 31, 2023		348,808,082					200
Balance at Mar. 31, 2023	$ 15,749,371	$ 1,799,920	8,412,085	5,782,958	(36,191)	5,537,877	$ 0	2,810,242	2,727,367	268
Balance (in shares) at Dec. 31, 2022	348,443,855	348,443,855					200
Balance at Dec. 31, 2022	$ 15,473,158	$ 1,799,920	8,401,731	5,527,153	(39,421)	5,700,670	$ 0	2,778,942	2,921,444	284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	510,340					268,556
Other Comprehensive Income (Loss)	$ 7,318					(43)
Balance (in shares) at Jun. 30, 2023	349,021,936	349,021,936					200
Balance at Jun. 30, 2023	$ 15,554,098	$ 1,799,920	8,428,786	5,562,889	(32,103)	5,753,103	$ 0	2,891,242	2,861,620	241
Balance (in shares) at Mar. 31, 2023		348,808,082					200
Balance at Mar. 31, 2023	15,749,371	$ 1,799,920	8,412,085	5,782,958	(36,191)	5,537,877	$ 0	2,810,242	2,727,367	268
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	17,302			17,302		134,743			134,743
Dividends on Preferred Stock	(1,880)			(1,880)		(490)			(490)
Dividends on Common Stock	(235,491)			(235,491)
Capital Contributions from Eversource Parent						81,000		81,000
Other Comprehensive Income (Loss)	$ 4,088				4,088	(27)				(27)
Balance (in shares) at Jun. 30, 2023	349,021,936	349,021,936					200
Balance at Jun. 30, 2023	$ 15,554,098	$ 1,799,920	$ 8,428,786	$ 5,562,889	$ (32,103)	$ 5,753,103	$ 0	$ 2,891,242	$ 2,861,620	$ 241