Goodwill Assets	6 Months Ended
Jun. 30, 2013
Goodwill And Other Intangible Assets [Abstract]
Goodwill And Other Intangible Assets	Goodwill Assets In accordance with the provisions for goodwill accounting under GAAP, NiSource tests its goodwill for impairment annually as of May 1 each year unless indicators, events, or circumstances would require an immediate review. Goodwill is tested for impairment at a level of reporting referred to as a reporting unit, which generally is an operating segment or a component of an operating segment as defined by the FASB. NiSource's three reporting units are Columbia Distribution Operations, Columbia Transmission Operations and Northern Indiana Gas Distribution Operations. NiSource's goodwill assets as of June 30, 2013 were $3.7 billion pertaining primarily to the acquisition of Columbia on November 1, 2000. Of this amount, approximately $2.0 billion is allocated to Columbia Transmission Operations and $1.7 billion is allocated to Columbia Distribution Operations. In addition, Northern Indiana Gas Distribution Operations' goodwill assets at June 30, 2013 related to the purchase of Northern Indiana Fuel and Light in March 1993 and Kokomo Gas in February 1992 were $17.8 million. NiSource completed a quantitative ("step 1") fair value measurement of its reporting units during the May 1, 2012 goodwill test. The test indicated that the fair value of each of the reporting units that carry or are allocated goodwill substantially exceeded their carrying values, indicating that no impairment existed under the step 1 annual impairment test. In September 2011, FASB issued Accounting Standards Update 2011-08, which allows entities testing goodwill for impairment the option of performing a qualitative ("step 0") assessment before calculating the fair value of a reporting unit for the goodwill impairment test. If a step 0 assessment is performed, an entity is no longer required to calculate the fair value of a reporting unit unless the entity determines that based on the qualitative step 0 assessment that it is more likely than not that its fair value is less than its carrying amount. The update was effective for fiscal years, and interim periods within those years, beginning after December 15, 2011. NiSource applied this guidance for its 2013 annual test and applied the qualitative step 0 analysis to its reporting units for the annual impairment test performed as of May 1, 2013. For the current year qualitative step 0 test performed as of May 1, 2013, NiSource assessed various assumptions, events and circumstances that would have affected the estimated fair value of the reporting units in its base line May 1, 2012 test. The results of this assessment indicated that it is not more likely than not that its reporting unit fair values are less than the reporting unit carrying values and no impairments are necessary. NiSource considered whether there were any events or changes in circumstances subsequent to the annual test that would reduce the fair value of any of the reporting units below their carrying amounts and necessitate another goodwill impairment test. No such indicators were noted that would require a subsequent goodwill impairment testing during the second quarter. During the first quarter of 2013, as part of the sale of the service plan and leasing business lines of its Retail Services business, NiSource allocated $10.0 million of goodwill from Columbia Distribution Operations to the sale and allocated $1.0 million of goodwill from Northern Indiana Gas Distribution Operations to the sale. Refer to Note 4 "Discontinued Operations and Assets and Liabilities Held for Sale" for more information.

Goodwill Assets

6 Months Ended

Jun. 30, 2013

Goodwill And Other Intangible Assets [Abstract]

Goodwill Assets

In accordance with the provisions for goodwill accounting under GAAP, NiSource tests its goodwill for impairment annually as of May 1 each year unless indicators, events, or circumstances would require an immediate review. Goodwill is tested for impairment at a level of reporting referred to as a reporting unit, which generally is an operating segment or a component of an operating segment as defined by the FASB. NiSource's three reporting units are Columbia Distribution Operations, Columbia Transmission Operations and Northern Indiana Gas Distribution Operations.

NiSource's goodwill assets as of June 30, 2013 were $3.7 billion pertaining primarily to the acquisition of Columbia on November 1, 2000. Of this amount, approximately $2.0 billion is allocated to Columbia Transmission Operations and $1.7 billion is allocated to Columbia Distribution Operations. In addition, Northern Indiana Gas Distribution Operations' goodwill assets at June 30, 2013 related to the purchase of Northern Indiana Fuel and Light in March 1993 and Kokomo Gas in February 1992 were $17.8 million.

NiSource completed a quantitative ("step 1") fair value measurement of its reporting units during the May 1, 2012 goodwill test. The test indicated that the fair value of each of the reporting units that carry or are allocated goodwill substantially exceeded their carrying values, indicating that no impairment existed under the step 1 annual impairment test.

In September 2011, FASB issued Accounting Standards Update 2011-08, which allows entities testing goodwill for impairment the option of performing a qualitative ("step 0") assessment before calculating the fair value of a reporting unit for the goodwill impairment test. If a step 0 assessment is performed, an entity is no longer required to calculate the fair value of a reporting unit unless the entity determines that based on the qualitative step 0 assessment that it is more likely than not that its fair value is less than its carrying amount. The update was effective for fiscal years, and interim periods within those years, beginning after December 15, 2011.

NiSource applied this guidance for its 2013 annual test and applied the qualitative step 0 analysis to its reporting units for the annual impairment test performed as of May 1, 2013.

For the current year qualitative step 0 test performed as of May 1, 2013, NiSource assessed various assumptions, events and circumstances that would have affected the estimated fair value of the reporting units in its base line May 1, 2012 test. The results of this assessment indicated that it is not more likely than not that its reporting unit fair values are less than the reporting unit carrying values and no impairments are necessary.

NiSource considered whether there were any events or changes in circumstances subsequent to the annual test that would reduce the fair value of any of the reporting units below their carrying amounts and necessitate another goodwill impairment test. No such indicators were noted that would require a subsequent goodwill impairment testing during the second quarter.

During the first quarter of 2013, as part of the sale of the service plan and leasing business lines of its Retail Services business, NiSource allocated $10.0 million of goodwill from Columbia Distribution Operations to the sale and allocated $1.0 million of goodwill from Northern Indiana Gas Distribution Operations to the sale. Refer to Note 4 "Discontinued Operations and Assets and Liabilities Held for Sale" for more information.