v2.3.0.11

Short-Term Borrowings (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended	6 Months Ended	3 Months Ended		3 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Nisource Finance [Member]	Jun. 30, 2011 Nisource Finance [Member]	Mar. 31, 2011 Nisource Finance [Member] Four-Year Revolving Credit Facility [Member]	Mar. 03, 2011 Nisource Finance [Member] Four-Year Revolving Credit Facility [Member]	Mar. 31, 2011 Nisource Finance [Member] Five-Year Credit Facility [Member]	Jun. 30, 2011 Nisource Finance [Member] Five-Year Credit Facility [Member]	Jun. 30, 2011 Letters of Credit [Member]	Dec. 31, 2010 Letters of Credit [Member]	Jun. 30, 2011 Revolving Credit Facility [Member]	Jun. 30, 2011 Four-Year Revolving Credit Facility [Member]	Dec. 31, 2010 Four-Year Revolving Credit Facility [Member]
Revolving credit facility			$ 500.0	$ 500.0		$ 1,500.0	$ 1,500.0	$ 1,500.0
Commercial paper	180.5
Commercial paper weighted average interest rate	0.95%
Revolving credit facility, termination date			March 2015	March 3, 2015	March 3, 2015		July 2011
Accounts receivable securitization agreements outstanding	183.9	275.0	183.9	183.9					183.9	275.0
Short-term borrowings	870.4	1,382.5
Letters of credit facility amount outstanding	$ 506.0	$ 1,107.5	$ 506.0	$ 506.0					$ 38.0	$ 32.5	$ 19.7	$ 506.0	$ 14.2
Credit facilities borrowings weighted average interest rate	1.90%	0.78%

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Commercial Paper Weighted Average Interest Rate

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Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(2))
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Amount borrowed under the credit facility as of the balance sheet date.

+ References

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Reflects when the credit facility terminates, which may be presented in a variety of ways (year, month and year, day, month and year, quarter).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 129
-Paragraph 2, 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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-Publisher FASB
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

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Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of short-term debt outstanding by type or by instrument at that time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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Carrying amount of liabilities associated with financial assets accounted for as secured borrowings recognized in the transferor's statement of financial position at the end of each period presented.

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