Consolidated Balance Sheet (Parenthetical) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accounts receivable - customers, allowance for uncollectible accounts	$ 85	$ 87
Other receivables, allowance for uncollectible accounts	10	10
Non-utility property, accumulated depreciation	66	59
Intangible assets, accumulated amortization	3	3
CECONY [Member]
Accounts receivable - customers, allowance for uncollectible accounts	79	79
Other receivables, allowance for uncollectible accounts	9	9
Non-utility property, accumulated depreciation	$ 25	$ 24