Note 4 - Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2012

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

In millions	June 30, 2012		December 31, 2011		June 30, 2011
Long-term debt amortized cost (1)	$	3,564	$	3,576	$	2,174
Long-term debt fair value (1) (2)	$	4,043	$	3,938	$	2,339

Natural Gas Derivatives [Member]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Recurring fair values Derivative instruments
	June 30, 2012						December 31, 2011					June 30, 2011
In millions	Assets			Liabilities			Assets (1)		Liabilities			Assets		Liabilities
Natural gas derivatives
Quoted prices in active markets (Level 1)		$	9	$	(103	)	$	11	$	(145	)	$	1	$	(52	)
Significant other observable inputs (Level 2)			148		(48	)		229		(68	)		99		(17	)
Netting of cash collateral			52		85			32		115			37		40
Total carrying value (2) (3)		$	209	$	(66	)	$	272	$	(98	)	$	137	$	(29	)
Interest rate derivatives
Significant other observable inputs (Level 2)		$	17	$	0		$	13	$	(13	)	$	3	$	0

Money Market Funds [Member]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

In millions	June 30, 2012		December 31, 2011		June 30, 2011
Money market funds (1)	$	76	$	59	$	0