Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Measurements [Abstract]

Fair Value Assets and Liabilities Measured On Recurring Basis [Text Block]

								Fair Value Measurements Using
									Quoted
									Prices In
									Active		Significant
									Markets for		Other		Significant
									Identical		Observable		Unobservable
				Carrying		Fair			Assets		Inputs		Inputs
				Amount		Value			(Level 1)		(Level 2)		(Level 3)
				(Millions)
Assets (liabilities) at December 31, 2012:
	Measured on a recurring basis:
		ARO Trust investments		$	18	$	18		$	18	$	-	$	-
		Energy derivatives assets not designated as
			hedging instruments		5		5			-		-		5
		Energy derivatives liabilities not designated as
			hedging instruments		(1)		(1)			-		-		(1)
	Additional disclosures:
		Notes receivable and other			95		138			2		8		128
		Long-term debt, including current portion (a)			(10,734)		(12,388)			-		(12,388)		-
		Guarantee			(33)		(31)			-		(31)		-
Assets (liabilities) at December 31, 2011:
	Measured on a recurring basis:
		ARO Trust investments		$	25	$	25		$	25	$	-	$	-
		Available-for-sale equity securities			24		24			24		-		-
		Energy derivatives assets not designated as
			hedging instruments		1		1			1		-		-
	Additional disclosures:
		Notes receivable and other			57		57			N/A		N/A		N/A
		Long-term debt, including current portion (a)			(8,718)		(10,043)			N/A		N/A		N/A
		Guarantee			(34)		(32)			N/A		N/A		N/A
(a) Excludes capital leases