Note 10 - Non-Wholly Owned Entities (Detail) - Additional Information on SouthStar’s Revenues and Expenses (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating revenues	$ 3,922	$ 2,338	$ 2,373
Operating expenses
Cost of goods sold	1,791	1,097	1,164
Operation and maintenance	921	501	497
Depreciation and amortization	415	186	160
Taxes other than income taxes	165	57	46
Total operating expenses	3,312	1,898	1,873
Operating income	610	440	500
South Star [Member]
Operating revenues	576	689
Operating expenses
Cost of goods sold	411	526
Operation and maintenance	63	67
Depreciation and amortization	2	2
Taxes other than income taxes	2	2
Total operating expenses	478	597
Operating income	$ 98	$ 92