Income Tax - Income Tax Reconciliation (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
STATUTORY TAX RATE
Federal	21.00%	21.00%	21.00%	21.00%
Changes in computed taxes resulting from:
State income tax	6.00%	5.00%	5.00%	5.00%
Amortization of excess deferred federal income taxes	(7.00%)	(3.00%)	(10.00%)	(3.00%)
Taxes attributable to non-controlling interest	(1.00%)	(1.00%)	(1.00%)	(2.00%)
Cost of removal	1.00%	1.00%	2.00%	1.00%
Other plant-related items	(1.00%)	(1.00%)	(1.00%)	0.00%
Renewable energy credits	(1.00%)	(1.00%)	(2.00%)	(2.00%)
Amortization of excess deferred state income taxes	0.00%	(1.00%)	0.00%	(1.00%)
Reserve for uncertain tax positions	0.00%	1.00%
Prior period federal income tax return adjustments	0.00%	(2.00%)	0.00%	(1.00%)
Other	1.00%	0.00%	0.00%	0.00%
Effective tax rate	19.00%	19.00%	14.00%	18.00%
CECONY
STATUTORY TAX RATE
Federal	21.00%	21.00%	21.00%	21.00%
Changes in computed taxes resulting from:
State income tax	5.00%	6.00%	5.00%	6.00%
Amortization of excess deferred federal income taxes	(8.00%)	(3.00%)	(10.00%)	(3.00%)
Taxes attributable to non-controlling interest	0.00%	0.00%	0.00%	0.00%
Cost of removal	2.00%	0.00%	2.00%	1.00%
Other plant-related items	(1.00%)	0.00%	(2.00%)	(1.00%)
Renewable energy credits	0.00%	0.00%	0.00%	0.00%
Amortization of excess deferred state income taxes	0.00%	(1.00%)	0.00%	(1.00%)
Reserve for uncertain tax positions	0.00%	0.00%
Prior period federal income tax return adjustments	0.00%	0.00%	0.00%	0.00%
Other	0.00%	(1.00%)	1.00%	(1.00%)
Effective tax rate	19.00%	22.00%	17.00%	22.00%

Effective Income Tax Rate Reconciliation, cost of removal

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Federal Statutory Income Tax Rate [Abstract]

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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