Note 3 - Regulated Operations (Details) - Summary of Regulatory Assets and Liabilities (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013
Regulatory assets
Regulatory assets, current	$ 250	[1]	$ 114	[1]	$ 72	[1]
Regulatory assets, long-term	696	[1]	705	[1]	868	[1]
Total regulatory assets	946	[1]	819	[1]	940	[1]
Regulatory liabilities
Regulatory liabilities, current	161	[1]	183	[1]	238	[1]
Regulatory liabilities, long-term	1,550	[1]	1,518	[1]	1,498	[1]
Total regulatory liabilities	1,711	[1]	1,701	[1]	1,736	[1]
Bad Debt Rider [Member]
Regulatory liabilities
Regulatory liabilities, current	41	[1]	41	[1]	39	[1]
Regulatory liabilities, long-term	14	[1]	17	[1]	20	[1]
Accumulated removal costs [Member]
Regulatory liabilities
Regulatory liabilities, current	27	[1]	27	[1]	17	[1]
Regulatory liabilities, long-term	1,456	[1]	1,445	[1]	1,413	[1]
Accrued natural gas costs [Member]
Regulatory liabilities
Regulatory liabilities, current	24	[1]	92	[1]	133	[1]
Seasonal Rates [Member]
Regulatory liabilities
Regulatory liabilities, current	20	[1]		[1]	20	[1]
Other Regulatory Liabilities [Member]
Regulatory liabilities
Regulatory liabilities, current	49	[1]	23	[1]	29	[1]
Regulatory liabilities, long-term	28	[1]	3	[1]	11	[1]
Regulatory Income Tax Liability [Member]
Regulatory liabilities
Regulatory liabilities, long-term	27	[1]	27	[1]	26	[1]
Unamortized investment tax credit [Member]
Regulatory liabilities
Regulatory liabilities, long-term	25	[1]	26	[1]	28	[1]
Deferred Natural Gas Costs [Member]
Regulatory assets
Regulatory assets, current	161	[1]	1	[1]		[1]
Recoverable Environmental Remediation Costs [Member]
Regulatory assets
Regulatory assets, current	38	[1]	45	[1]	28	[1]
Regulatory assets, long-term	419	[1]	433	[1]	415	[1]
Recoverable Pension And Other Retirement Benefit Costs [Member]
Regulatory assets
Regulatory assets, current	9	[1]	9	[1]	19	[1]
Regulatory assets, long-term	97	[1]	99	[1]	192	[1]
Other Regulatory Assets [Member]
Regulatory assets
Regulatory assets, current	42	[1]	59	[1]	25	[1]
Regulatory assets, long-term	43	[1]	36	[1]	48	[1]
Recoverable Regulatory Infrastructure Program Costs [Member]
Regulatory assets
Regulatory assets, long-term	57	[1]	55	[1]	125	[1]
Long-Term Debt Fair Value Adjustment [Member]
Regulatory assets
Regulatory assets, long-term	$ 80	[1]	$ 82	[1]	$ 88	[1]

[1] Amounts revised to include prior period adjustments. See Note 13 for additional information.