Note 2 - Significant Accounting Policies and Methods of Application (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	9 Months Ended			9 Months Ended				1 Months Ended	8 Months Ended	9 Months Ended				1 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2013 Net of Tax [Member] Compass Energy [Member]	Sep. 30, 2013 Midstream Operations [Member]	Dec. 31, 2012 Midstream Operations [Member]	Sep. 30, 2012 Midstream Operations [Member]	Sep. 30, 2013 Proposed Rate [Member] Nicor Gas [Member]	Aug. 29, 2013 Current Rate [Member] Nicor Gas [Member]	Sep. 30, 2013 Compass Energy [Member]	Sep. 30, 2013 Tropical Shipping [Member]	Dec. 31, 2012 Tropical Shipping [Member]	Sep. 30, 2012 Tropical Shipping [Member]	Jan. 31, 2013 NiSource Inc. [Member] Customer Relationships [Member]	Jan. 31, 2013 NiSource Inc. [Member] Trade Names [Member]	Jan. 31, 2013 NiSource Inc. [Member]	Jun. 30, 2013 Customer Relationships [Member]	Jun. 30, 2013 Minimum [Member] Customer Relationships [Member]	Jun. 30, 2013 Maximum [Member] Customer Relationships [Member]
Note 2 - Significant Accounting Policies and Methods of Application (Details) [Line Items]
Investments and Cash												$ 74	$ 80	$ 76
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service									3.07%	4.10%
Reduction in Depreciation Expense	4
Goodwill	1,883	1,883	1,837	1,817		14	14	14									46
Percent Goodwill Exceeds Carrying Value							10.00%
Service Plans Acquired																	500,000
Payments to Acquire Businesses, Gross																	120
Working Capital Acquired																	2
Finite-lived Intangible Assets Acquired															47	17
Finite-Lived Intangible Asset, Useful Life															14 years	10 years			14 years	16 years
Customer Relationships Acquired																		33,000
Finite-Lived Customer Relationships, Gross																		32
Proceeds from Sales of Business, Affiliate and Productive Assets		12									12
Gain (Loss) on Disposition of Business					5						11
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High											8
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low											$ 3
Business Combination Contingent Consideration Arrangements Earn Out Period											5 years