Note 8 - Non-Wholly Owned Entities (Details) - SouthStar’s Revenues and Expenses (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Variable Interest Entity [Line Items]
Operating revenues	$ 904	$ 686	$ 2,613	$ 2,090
Operating expenses
Cost of goods sold	407	240	1,380	959
Operation and maintenance	233	218	492	463
Depreciation and amortization	109	102	216	206
Taxes other than income taxes	44	32	115	96
Total operating expenses	793	595	2,203	1,737
Operating income	122	91	421	353
South Star [Member]
Variable Interest Entity [Line Items]
Operating revenues	116	99	366	314
Operating expenses
Cost of goods sold	95	80	259	213
Operation and maintenance	15	12	33	31
Depreciation and amortization		1	1	1
Taxes other than income taxes	1	1	1	2
Total operating expenses	111	94	294	247
Operating income	$ 5	$ 5	$ 72	$ 67