Note 8 - Non-Wholly Owned Entities (Detail) - SouthStar’s Revenues and Expenses (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating revenues	$ 1,709	$ 1,404
Operating expenses
Cost of goods sold	973	719
Operation and maintenance	259	245
Depreciation and amortization	107	104
Taxes other than income taxes	71	64
Total operating expenses	1,410	1,142
Operating income	299	262
South Star [Member]
Operating revenues	250	215
Operating expenses
Cost of goods sold	164	133
Operation and maintenance	18	19
Depreciation and amortization	1
Taxes other than income taxes		1
Total operating expenses	183	153
Operating income	$ 67	$ 62