THE CONNECTICUT LIGHT AND POWER COMPANY CONDENSED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital Surplus, Paid In	Retained Earnings	Accumulated Other Comprehensive Loss	The Connecticut Light and Power Company	The Connecticut Light and Power Company Common Stock	The Connecticut Light and Power Company Capital Surplus, Paid In	The Connecticut Light and Power Company Retained Earnings	The Connecticut Light and Power Company Accumulated Other Comprehensive Loss
Balance (in shares) at Dec. 31, 2021		344,403,196					6,035,205
Balance at Dec. 31, 2021	$ 14,599,844	$ 1,789,092	$ 8,098,514	$ 5,005,391	$ (42,275)	$ 5,299,501	$ 60,352	$ 3,010,765	$ 2,228,133	$ 251
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	445,326			445,326		152,977			152,977
Dividends on Preferred Stock	(1,880)			(1,880)		(1,390)			(1,390)
Dividends on Common Stock	(219,768)			(219,768)		(73,100)			(73,100)
Capital Contributions from Eversource Parent						100,000		100,000
Other comprehensive income (loss)						(35)				(35)
Balance (in shares) at Mar. 31, 2022		344,850,272					6,035,205
Balance at Mar. 31, 2022	14,836,690	$ 1,789,092	8,102,618	5,229,069	(41,571)	5,477,953	$ 60,352	3,110,765	2,306,620	216
Balance (in shares) at Dec. 31, 2021		344,403,196					6,035,205
Balance at Dec. 31, 2021	14,599,844	$ 1,789,092	8,098,514	5,005,391	(42,275)	5,299,501	$ 60,352	3,010,765	2,228,133	251
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income						422,102
Other comprehensive income (loss)						(88)
Balance (in shares) at Sep. 30, 2022		347,348,749					6,035,205
Balance at Sep. 30, 2022	15,279,173	$ 1,799,920	8,327,477	5,429,076	(41,006)	5,698,045	$ 60,352	3,210,765	2,426,765	163
Balance (in shares) at Mar. 31, 2022		344,850,272					6,035,205
Balance at Mar. 31, 2022	14,836,690	$ 1,789,092	8,102,618	5,229,069	(41,571)	5,477,953	$ 60,352	3,110,765	2,306,620	216
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	293,742			293,742		125,838			125,838
Dividends on Preferred Stock	(1,880)			(1,880)		(1,390)			(1,390)
Dividends on Common Stock	(219,877)			(219,877)		(73,100)			(73,100)
Capital Contributions from Eversource Parent						100,000		100,000
Other comprehensive income (loss)						(23)				(23)
Balance (in shares) at Jun. 30, 2022		346,411,029					6,035,205
Balance at Jun. 30, 2022	15,057,215	$ 1,796,056	8,242,346	5,301,054	(42,864)	5,629,278	$ 60,352	3,210,765	2,357,968	193
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	351,289			351,289		143,287			143,287
Dividends on Preferred Stock	(1,880)			(1,880)		(1,390)			(1,390)
Dividends on Common Stock	(221,387)			(221,387)		(73,100)			(73,100)
Other comprehensive income (loss)						(30)				(30)
Balance (in shares) at Sep. 30, 2022		347,348,749					6,035,205
Balance at Sep. 30, 2022	$ 15,279,173	$ 1,799,920	8,327,477	5,429,076	(41,006)	5,698,045	$ 60,352	3,210,765	2,426,765	163
Balance (in shares) at Dec. 31, 2022	348,443,855	348,443,855					6,035,205
Balance at Dec. 31, 2022	$ 15,473,158	$ 1,799,920	8,401,731	5,527,153	(39,421)	5,784,380	$ 60,352	3,260,765	2,463,094	169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	493,039			493,039		148,416			148,416
Dividends on Preferred Stock	(1,880)			(1,880)		(1,390)			(1,390)
Dividends on Common Stock	(235,354)			(235,354)		(82,600)			(82,600)
Other comprehensive income (loss)						36				36
Balance (in shares) at Mar. 31, 2023		348,808,082					6,035,205
Balance at Mar. 31, 2023	$ 15,749,371	$ 1,799,920	8,412,085	5,782,958	(36,191)	5,848,842	$ 60,352	3,260,765	2,527,520	205
Balance (in shares) at Dec. 31, 2022	348,443,855	348,443,855					6,035,205
Balance at Dec. 31, 2022	$ 15,473,158	$ 1,799,920	8,401,731	5,527,153	(39,421)	5,784,380	$ 60,352	3,260,765	2,463,094	169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income						401,104
Other comprehensive income (loss)						22
Balance (in shares) at Sep. 30, 2023	349,275,775	349,275,775					6,035,205
Balance at Sep. 30, 2023	$ 15,685,941	$ 1,799,920	8,443,820	5,666,861	(24,022)	6,057,036	$ 60,352	3,384,265	2,612,228	191
Balance (in shares) at Mar. 31, 2023		348,808,082					6,035,205
Balance at Mar. 31, 2023	15,749,371	$ 1,799,920	8,412,085	5,782,958	(36,191)	5,848,842	$ 60,352	3,260,765	2,527,520	205
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	17,302			17,302		133,300			133,300
Dividends on Preferred Stock	(1,880)			(1,880)		(1,390)			(1,390)
Dividends on Common Stock	(235,491)			(235,491)		(82,600)			(82,600)
Other comprehensive income (loss)						(7)				(7)
Balance (in shares) at Jun. 30, 2023		349,021,936					6,035,205
Balance at Jun. 30, 2023	15,554,098	$ 1,799,920	8,428,786	5,562,889	(32,103)	5,898,145	$ 60,352	3,260,765	2,576,830	198
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	341,543			341,543		119,388			119,388
Dividends on Preferred Stock	(1,880)			(1,880)		(1,390)			(1,390)
Dividends on Common Stock	$ (235,691)			(235,691)		(82,600)			(82,600)
Capital Contributions from Eversource Parent						123,500		123,500
Other comprehensive income (loss)						(7)				(7)
Balance (in shares) at Sep. 30, 2023	349,275,775	349,275,775					6,035,205
Balance at Sep. 30, 2023	$ 15,685,941	$ 1,799,920	$ 8,443,820	$ 5,666,861	$ (24,022)	$ 6,057,036	$ 60,352	$ 3,384,265	$ 2,612,228	$ 191