Regulatory Matters Regulatory Matters - Regulatory Assets (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	$ 6,935	$ 7,024
Regulatory assets – current	77	100
Total Regulatory Assets	7,012	7,124
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,768	2,874
Future income tax
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,413	2,439
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	807	823
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	327	295
Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	77	48
Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	59	38
Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	54	44
Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	44	56
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	40	43
Indian Point Energy Center program costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	40	50
Surcharge for New York State assessment
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	32	28
O&R property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	32	37
Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	26	29
Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	25	25
Net electric deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	17	24
Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	15	42
Regulatory assets – current	6	9
Workers’ compensation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	13
O&R transition bond charges
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	12	15
Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	133	101
Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – current	71	91
CECONY
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	6,404	6,473
Regulatory assets – current	68	90
Total Regulatory Assets	6,472	6,563
CECONY | Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,612	2,730
CECONY | Future income tax
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,302	2,325
CECONY | Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	697	711
CECONY | Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	311	280
CECONY | Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	70	42
CECONY | Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	32	7
CECONY | Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	54	44
CECONY | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	3
CECONY | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	38	41
CECONY | Indian Point Energy Center program costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	40	50
CECONY | Surcharge for New York State assessment
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	30	26
CECONY | O&R property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	0
CECONY | Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	26	29
CECONY | Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	25	25
CECONY | Net electric deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	17	24
CECONY | Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	15	38
Regulatory assets – current	3	4
CECONY | Workers’ compensation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	13
CECONY | O&R transition bond charges
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	0
CECONY | Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	121	85
CECONY | Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – current	$ 65	$ 86