Derivative Instruments and Hedging Activities - Realized and Unrealized Gains (Losses) on Commodity Derivatives (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ (275)	$ 384
Total deferred gains/(losses)	(440)	87
Net deferred gains/(losses)	(715)	471
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	26	56
Gas purchased for resale
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	4	5
Other operations and maintenance expense
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	3
Other interest expense
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	5	65
Non-utility
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	17	(17)
Deferred Derivative Gains, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(149)	339
Deferred Derivative Gains, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(126)	45
Deferred Derivative Losses, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(16)	(36)
Recoverable Energy Costs, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(291)	157
Deferred Derivative Losses, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(133)	(34)
CECONY | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(248)	353
Total deferred gains/(losses)	(416)	77
Net deferred gains/(losses)	(664)	430
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	3
CECONY | Gas purchased for resale | Subsidiaries
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0
CECONY | Other operations and maintenance expense | Subsidiaries
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	3
CECONY | Other interest expense | Subsidiaries
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0
CECONY | Non-utility | Subsidiaries
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	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)	(137)	312
CECONY | Deferred Derivative Gains, Noncurrent | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(111)	41
CECONY | Deferred Derivative Losses, Current | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(12)	(32)
CECONY | Recoverable Energy Costs, Current | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(274)	143
CECONY | Deferred Derivative Losses, Noncurrent | Subsidiaries
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ (130)	$ (34)