CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 646	$ 220
Accounts and notes receivable, net	222	201
Other	77	65
Other Assets:
Regulatory assets	3,388	3,726
Variable Interest Entity [Member]
Current Assets:
Cash and cash equivalents	266	220
Accounts and notes receivable, net	68	52
Other	54	42
Other Assets:
Regulatory assets	$ 3,545	$ 2,289