Note 8 - Non-Wholly Owned Entities (Details) - SouthStar’s Revenues and Expenses (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Variable Interest Entity [Line Items]
Operating revenues	$ 675	$ 614	$ 3,288	$ 2,704
Operating income	82	54	503	407
Cost of goods sold	229	215	1,609	1,174
Operation and maintenance	226	212	718	675
Depreciation and amortization	109	104	325	310
Taxes other than income taxes	29	27	144	123
Total operating expenses	593	560	2,796	2,297
South Star [Member]
Variable Interest Entity [Line Items]
Operating revenues	98	87	464	401
Operating income			72	67
Cost of goods sold	81	73	340	286
Operation and maintenance	16	13	49	44
Depreciation and amortization	1	1	2	2
Taxes other than income taxes			1	2
Total operating expenses	$ 98	$ 87	$ 392	$ 334