Report of Business Segments (Tables)

9 Months Ended

Sep. 30, 2013

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

The following tables summarize the results of the Company's business segments during the three and ninemonths endedSeptember 30, 2013 and 2012.

Three Months Ended September 30, 2013	Electric Utility		Natural Gas Midstream Operations		Other Operations			Eliminations			Total
(In millions)
Operating revenues	$	723.2	$	—	$	—		$	—		$	723.2
Cost of goods sold	273.0		—		—			—			273.0
Gross margin on revenues	450.2		—		—			—			450.2
Other operation and maintenance	105.9		—		(3.7		)	—			102.2
Depreciation and amortization	62.5		—		2.9			—			65.4
Taxes other than income	20.8		—		0.9			—			21.7
Operating income (loss)	$	261.0	$	—	$	(0.1	)	$	—		$	260.9
Equity in earnings of unconsolidated affiliates	$	—	$	46.0	$	—		$	—		$	46.0
Investment in unconsolidated affiliates (at historical cost)	$	—	$	1,295.8	$	—		$	—		$	1,295.8
Total assets	$	7,704.0	$	1,311.3	$	172.2		$	(43.3	)	$	9,144.2

Three Months Ended September 30, 2012	Electric Utility		Natural Gas Midstream Operations		Other Operations			Eliminations			Total
(In millions)
Operating revenues	$	721.0	$	412.4	$	—		$	(20.0	)	$	1,113.4
Cost of goods sold	271.8		288.6		—			(20.8		)	539.6
Gross margin on revenues	449.2		123.8		—			0.8			573.8
Other operation and maintenance	108.6		42.3		(3.8		)	—			147.1
Depreciation and amortization	63.5		26.5		3.0			—			93.0
Taxes other than income	19.1		9.8		0.8			—			29.7
Operating income (loss)	$	258.0	$	45.2	$	—		$	0.8		$	304.0
Total assets	$	7,082.3	$	2,562.7	$	276.6		$	(215.6	)	$	9,706.0

Nine Months Ended September 30, 2013	Electric Utility		Natural Gas Midstream Operations		Other Operations			Eliminations			Total
(In millions)
Operating revenues	$	1,753.3	$	630.4	$	—		$	(24.9	)	$	2,358.8
Cost of goods sold	733.6		489.0		—			(26.0		)	1,196.6
Gross margin on revenues	1,019.7		141.4		—			1.1			1,162.2
Other operation and maintenance	318.0		60.9		(6.7		)	—			372.2
Depreciation and amortization	185.8		36.8		9.1			—			231.7
Taxes other than income	63.9		10.5		3.7			—			78.1
Operating income (loss)	$	452.0	$	33.2	$	(6.1	)	$	1.1		$	480.2
Equity in earnings of unconsolidated affiliates	$	—	$	64.5	$	—		$	—		$	64.5
Investment in unconsolidated affiliates (at historical cost)	$	—	$	1,295.8	$	—		$	—		$	1,295.8
Total assets	$	7,704.0	$	1,311.3	$	172.2		$	(43.3	)	$	9,144.2

Nine Months Ended September 30, 2012	Electric Utility		Natural Gas Midstream Operations			Other Operations			Eliminations			Total
(In millions)
Operating revenues	$	1,675.7	$	1,186.0		$	—		$	(52.6	)	$	2,809.1
Cost of goods sold	671.9		816.5			—			(54.2		)	1,434.2
Gross margin on revenues	1,003.8		369.5			—			1.6			1,374.9
Other operation and maintenance	333.9		127.3			(13.5		)	—			447.7
Depreciation and amortization	185.9		74.2			10.0			—			270.1
Impairment of assets	—		0.3			—			—			0.3
Gain on insurance proceeds	—		(7.5		)	—			—			(7.5		)
Taxes other than income	58.4		22.8			3.5			—			84.7
Operating income (loss)	$	425.6	$	152.4		$	—		$	1.6		$	579.6
Total assets	$	7,082.3	$	2,562.7		$	276.6		$	(215.6	)	$	9,706.0