v2.3.0.11
Discontinued Operations and Assets and Liabilities Held for Sale (Assets and Liabilities of Discontinued Operations and Held for Sale) (Details) (USD $)
In Millions
Jun. 30, 2011
Dec. 31, 2010
Property, plant and equipment $ 2.3 $ 7.9
Other assets    
Total assets of discontinued operations and held for sale 2.3 7.9
Total liabilities of discontinued operations and held for sale   0
Ni Source Corporate Services [Member]
   
Property, plant and equipment   5.6
Other assets    
Total assets of discontinued operations and held for sale   5.6
Columbia Transmission [Member]
   
Property, plant and equipment 2.3 2.3
Other assets    
Total assets of discontinued operations and held for sale $ 2.3 $ 2.3