CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 206	$ 646
Accounts and notes receivable, net	227	222
Other	62	77
Other Assets:
Regulatory assets	3,309	3,388
Variable Interest Entity [Member]
Current Assets:
Cash and cash equivalents	166	266
Accounts and notes receivable, net	65	68
Other	53	54
Other Assets:
Regulatory assets	$ 3,470	$ 3,545