Note 5 - Derivative Instruments (Details) - Derivative Instruments on the Condensed Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Designated as cash flow hedges and fair value hedges
Net amounts of assets and liabilities presented in ourConsolidated Statements of Financial Position (3)	$ (80)		$ (39)
Designated as Hedging Instrument [Member] | Current Natural Gas Contracts [Member]
Designated as cash flow hedges and fair value hedges
Assets	3	[1],[2]	1	[1],[2]
Liabilities	(1)	[1],[2]	(2)	[1],[2]
Designated as Hedging Instrument [Member] | Long-Term Interest Rate Swap Agreements [Member]
Designated as cash flow hedges and fair value hedges
Assets		[1],[2]	3	[1],[2]
Liabilities		[1],[2]		[1],[2]
Designated as Hedging Instrument [Member] | Long-Term Natural Gas Contracts [Member]
Designated as cash flow hedges and fair value hedges
Assets	900	[1]	443	[1]
Liabilities	(982)	[1]	(407)	[1]
Gross amounts offset in our Consolidated Statements of Financial Position (2)	(781)	[2]	(299)	[2]
Gross amounts offset in our Consolidated Statements of Financial Position (2)	902	[2]	368	[2]
Designated as Hedging Instrument [Member]
Designated as cash flow hedges and fair value hedges
Assets	3	[1],[2]	4	[1],[2]
Liabilities	(1)	[1],[2]	(2)	[1],[2]
Net amounts of assets and liabilities presented in ourConsolidated Statements of Financial Position (3)	119	[3]	144	[3]
Net amounts of assets and liabilities presented in ourConsolidated Statements of Financial Position (3)	(80)	[3]	(39)	[3]
Not Designated as Hedging Instrument [Member] | Current Natural Gas Contracts [Member]
Designated as cash flow hedges and fair value hedges
Assets	691	[1],[2]	394	[1],[2]
Liabilities	(761)	[1],[2]	(355)	[1],[2]
Not Designated as Hedging Instrument [Member] | Long-Term Natural Gas Contracts [Member]
Designated as cash flow hedges and fair value hedges
Assets	206	[1],[2]	45	[1],[2]
Liabilities	(220)	[1],[2]	(50)	[1],[2]
Not Designated as Hedging Instrument [Member]
Designated as cash flow hedges and fair value hedges
Assets	897	[1],[2]	439	[1],[2]
Liabilities	$ (981)	[1],[2]	$ (405)	[1],[2]

[1] The gross amounts of recognized assets and liabilities are netted within our Consolidated Statements of Financial Position to the extent that we have netting arrangements with the counterparties.

[2] As required by the authoritative guidance related to derivatives and hedging, the gross amounts of recognized assets and liabilities above do not include cash collateral held on deposit in broker margin accounts of $121 million as of December 31, 2013 and $69 million as of December 31, 2012. Cash collateral is included in the "Gross amounts offset in our Consolidated Statements of Financial Position" line of this table.

[3] At December 31, 2013 and 2012 we held letters of credit from counterparties that would offset, under master netting arrangements, an insignificant portion of these assets.