Consolidated Statement of Capitalization - USD ($) shares in Millions, $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Schedule of Capitalization, Equity [Line Items]
TOTAL EQUITY BEFORE ACCUMULATED OTHER COMPREHENSIVE LOSS (in shares)	310	305
TOTAL EQUITY BEFORE ACCUMULATED OTHER COMPREHENSIVE LOSS	$ 15,444	$ 14,325
Pension plan liability adjustments, net of taxes	(23)	(24)
Unrealized losses on derivatives qualified as cash flow hedges, less reclassification adjustment for gains/(losses) included in net income and reclassification adjustment for unrealized losses included in regulatory assets, net of taxes	(3)	(3)
TOTAL ACCUMULATED OTHER COMPREHENSIVE LOSS, NET OF TAXES	(26)	(27)
Equity	15,418	14,298
Noncontrolling interest	7	8
TOTAL EQUITY (See Statement of Equity)	$ 15,425	$ 14,306
CECONY
Schedule of Capitalization, Equity [Line Items]
TOTAL EQUITY BEFORE ACCUMULATED OTHER COMPREHENSIVE LOSS (in shares)	235	235
TOTAL EQUITY BEFORE ACCUMULATED OTHER COMPREHENSIVE LOSS	$ 12,445	$ 11,836
Pension plan liability adjustments, net of taxes	(3)	(4)
Unrealized losses on derivatives qualified as cash flow hedges, less reclassification adjustment for gains/(losses) included in net income and reclassification adjustment for unrealized losses included in regulatory assets, net of taxes	(3)	(3)
TOTAL ACCUMULATED OTHER COMPREHENSIVE LOSS, NET OF TAXES	(6)	(7)
Equity	12,439	11,829
TOTAL SHAREHOLDER’S EQUITY (See Statement of Shareholder’s Equity)	$ 12,439	$ 11,829