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, 2022		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						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)						(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, 2023	349,540,266	349,540,266					200
Balance at Dec. 31, 2023	$ 14,173,892	$ 1,799,920	8,460,876	4,142,515	(33,737)	6,150,498	$ 0	3,013,842	3,136,612	44
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income						159,977			159,977
Dividends on Preferred Stock	(1,880)			(1,880)		(490)			(490)
Dividends on Common Stock	$ (250,770)			(250,770)		(96,700)			(96,700)
Capital Contributions from Eversource Parent						300,000		300,000
Other Comprehensive Income (Loss)						(16)				(16)
Balance (in shares) at Mar. 31, 2024	351,379,414	351,379,414					200
Balance at Mar. 31, 2024	$ 14,543,588	$ 1,806,385	$ 8,537,591	$ 4,413,593	$ (28,534)	$ 6,513,269	$ 0	$ 3,313,842	$ 3,199,399	$ 28