NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Thousands	Total	Adoption of New Accounting Standard	Common Stock	Capital Surplus, Paid In	Retained Earnings	Retained Earnings Adoption of New Accounting Standard	Accumulated Other Comprehensive Income (Loss)	NSTAR Electric	NSTAR Electric Adoption of New Accounting Standard	NSTAR Electric Common Stock	NSTAR Electric Capital Surplus, Paid In	NSTAR Electric Retained Earnings	NSTAR Electric Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2019			329,880,645							200
Beginning balance at Dec. 31, 2019	$ 12,629,994	$ (1,514)	$ 1,729,292	$ 7,087,768	$ 4,177,048	$ (1,514)	$ (65,059)	$ 4,159,884	$ (161)	$ 0	$ 1,813,442	$ 2,346,287	$ 155
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,212,686				1,212,686			445,001				445,001
Dividends on Preferred Stock	(7,519)				(7,519)			(1,960)				(1,960)
Dividends on Common Stock	(767,500)				(767,500)			(262,000)				(262,000)
Capital Contributions from Eversource Parent								180,500			180,500
Other Comprehensive Income/(Loss), Net of Tax	(11,352)						(11,352)	154					154
Ending balance (in shares) at Dec. 31, 2020			342,954,023							200
Ending balance at Dec. 31, 2020	14,063,566		$ 1,789,092	8,015,663	4,613,201		(76,411)	4,521,418		$ 0	1,993,942	2,527,167	309
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,228,046				1,228,046			476,569				476,569
Dividends on Preferred Stock	(7,519)				(7,519)			(1,960)				(1,960)
Dividends on Common Stock	(828,337)				(828,337)			(283,200)				(283,200)
Capital Contributions from Eversource Parent	160,000							260,000			260,000
Other Comprehensive Income/(Loss), Net of Tax	$ 34,136						34,136	192					192
Ending balance (in shares) at Dec. 31, 2021	344,403,196		344,403,196							200
Ending 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	1,412,394				1,412,394			492,428				492,428
Dividends on Preferred Stock	(7,519)				(7,519)			(1,960)				(1,960)
Dividends on Common Stock	(883,113)				(883,113)			(287,600)				(287,600)
Capital Contributions from Eversource Parent								525,000			525,000
Other Comprehensive Income/(Loss), Net of Tax	$ 2,854						2,854	(217)					(217)
Ending balance (in shares) at Dec. 31, 2022	348,443,855		348,443,855							200
Ending 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