Derivative Instruments and Hedging Activities - Realized and Unrealized Gains (Losses) on Commodity Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ 54	$ 366	$ 470	$ 549
Total deferred gains/(losses)	258	(48)	426	(21)
Net deferred gains/(losses)	312	318	896	528
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	45	(9)	140	32
Gas purchased for resale
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(2)	2	1	4
Non-utility revenue
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(1)	(23)	(23)	(22)
Other operations and maintenance expense
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(1)	1	4	5
Other interest expense
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	49	11	158	45
Deferred Derivative Gains, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	31	296	379	443
Deferred Derivative Gains, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	23	70	91	106
Deferred Derivative Losses, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	41	(4)	50	25
Recoverable Energy Costs, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	168	17	357	(30)
Deferred Derivative Losses, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	49	(61)	19	(16)
CECONY | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	47	345	429	512
Total deferred gains/(losses)	234	(45)	387	(20)
Net deferred gains/(losses)	281	300	816	492
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(1)	1	4	5
CECONY | Gas purchased for resale | Subsidiaries
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY | Non-utility revenue | Subsidiaries
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY | Other operations and maintenance expense | Subsidiaries
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(1)	1	4	5
CECONY | Other interest expense | Subsidiaries
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY | Deferred Derivative Gains, Current | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	30	279	350	415
CECONY | Deferred Derivative Gains, Noncurrent | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	17	66	79	97
CECONY | Deferred Derivative Losses, Current | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	37	(3)	45	22
CECONY | Recoverable Energy Costs, Current | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	152	13	324	(29)
CECONY | Deferred Derivative Losses, Noncurrent | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ 45	$ (55)	$ 18	$ (13)