Current Expected Credit Losses - Rollforward of Segment Type (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Accounts receivable - customers
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 615	$ 434	$ 620	$ 360
Recoveries	8	0	31	17
Write-offs	(134)	(65)	(352)	(160)
Reserve adjustments	121	92	311	244
Ending Balance	610	461	610	461
Other receivables
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	42	25	41	13
Recoveries	0	0	0	0
Write-offs	(2)	0	(6)	0
Reserve adjustments	20	(1)	25	11
Ending Balance	60	24	60	24
CECONY | Accounts receivable - customers | Subsidiaries
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	605	419	605	353
Recoveries	7	0	30	13
Write-offs	(132)	(63)	(346)	(152)
Reserve adjustments	120	92	311	234
Ending Balance	600	448	600	448
CECONY | Other receivables | Subsidiaries
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	35	21	38	9
Recoveries	0	0	0	0
Write-offs	(1)	0	(5)	0
Reserve adjustments	19	0	20	12
Ending Balance	$ 53	$ 21	$ 53	$ 21