Consolidated Balance Sheet (Parenthetical) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Accounts receivable - customers, allowance for uncollectible accounts	$ 87	$ 76
Other receivables, allowance for uncollectible accounts	10	8
Non-utility property, accumulated depreciation	59	51
Intangible assets, accumulated amortization	3	3
CECONY [Member]
Accounts receivable - customers, allowance for uncollectible accounts	79	68
Other receivables, allowance for uncollectible accounts	9	7
Non-utility property, accumulated depreciation	$ 24	$ 22