Note 4 - Derivative Instruments (Details) - Derivative Instruments on the Consolidated Statements of Income (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Not designated as hedges
Total (losses) on derivative instruments	$ (14)		$ (18)		$ (19)		$ (46)
Cash Flow Hedging [Member] | Cost of Sales [Member]
Designated as cash flow hedges
Natural gas contracts - gain reclassified from OCI	(1)		(2)				(2)
Cash Flow Hedging [Member] | Operating Expense [Member]
Designated as cash flow hedges
Natural gas contracts - gain reclassified from OCI			(2)				(1)
Cash Flow Hedging [Member] | Interest Expense [Member]
Designated as cash flow hedges
Interest rate swaps reclassified from OCI to interest expense	1		2		(2)		(1)
Fair Value Hedging [Member] | Cost of Sales [Member]
Not designated as hedges
Natural gas contracts - net value adjustments		[1]	1	[1]	(1)	[1]	(2)	[1]
Fair Value Hedging [Member] | Sales [Member]
Not designated as hedges
Natural gas contracts - net value adjustments	$ (14)	[2]	$ (17)	[2]	$ (16)	[2]	$ (40)	[2]

[1] Excludes losses recorded in operating revenues or cost of goods sold associated with weather derivatives of $3 million for the nine months ended September 30, 2013 and gains of $14 million for the nine months ended September 30, 2012.

[2] Associated with the fair value of existing derivative instruments at September 30, 2013 and 2012.