Business Segment Information (Tables)

6 Months Ended

Jun. 30, 2013

Segment Reporting [Abstract]

Schedule Of Operating Income Derived From Revenues And Expenses By Segment

	Three Months Ended June 30,						Six Months Ended June 30,
(in millions)	2013			2012			2013			2012
REVENUES
Gas Distribution Operations
Unaffiliated	$	572.4		$	443.8		$	1,717.3		$	1,503.9
Intersegment	—			0.1			0.2			0.3
Total	572.4			443.9			1,717.5			1,504.2
Columbia Pipeline Group Operations
Unaffiliated	242.3			209.5			500.7			442.5
Intersegment	31.5			31.5			74.5			73.9
Total	273.8			241.0			575.2			516.4
Electric Operations
Unaffiliated	384.9			377.2			762.3			730.1
Intersegment	0.2			0.2			0.4			0.4
Total	385.1			377.4			762.7			730.5
Corporate and Other
Unaffiliated	12.7			8.3			26.3			10.5
Intersegment	110.0			115.3			231.7			226.0
Total	122.7			123.6			258.0			236.5
Eliminations	(141.7		)	(147.1		)	(306.8		)	(300.6		)
Consolidated Gross Revenues	$	1,212.3		$	1,038.8		$	3,006.6		$	2,687.0
Operating Income (Loss)
Gas Distribution Operations	$	50.0		$	43.4		$	284.1		$	253.0
Columbia Pipeline Group Operations	88.8			91.5			222.3			230.1
Electric Operations	59.5			70.3			124.7			116.5
Corporate and Other	(4.8		)	(0.2		)	(9.5		)	2.4
Consolidated Operating Income	$	193.5		$	205.0		$	621.6		$	602.0