CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Utility revenues	$ 694.4	$ 563.6	$ 1,818.2	$ 1,534.6
Nonregulated revenues	421.6	276.0	976.0	552.9
Total revenues	1,116.0	839.6	2,794.2	2,087.5
Utility cost of fuel, natural gas, and purchased power	296.0	225.9	861.1	698.2
Nonregulated cost of sales	447.9	192.3	884.7	466.0
Operating and maintenance expense	288.7	249.0	583.8	508.3
Depreciation and amortization expense	65.5	62.6	126.4	124.7
Taxes other than income taxes	24.8	22.7	52.0	50.1
Operating income (loss)	(6.9)	87.1	286.2	240.2
Earnings from equity method investments	22.8	22.2	45.1	43.3
Miscellaneous income	5.5	1.7	11.2	4.1
Interest expense	(28.6)	(29.7)	(57.9)	(60.1)
Other expense	(0.3)	(5.8)	(1.6)	(12.7)
Income (loss) before taxes	(7.2)	81.3	284.6	227.5
Provision (benefit) for income taxes	(3.3)	29.6	106.3	77.0
Net income (loss) from continuing operations	(3.9)	51.7	178.3	150.5
Discontinued operations, net of tax	(0.8)	(2.1)	5.3	(1.2)
Net income (loss)	(4.7)	49.6	183.6	149.3
Preferred stock dividends of subsidiary	(0.8)	(0.8)	(1.6)	(1.6)
Noncontrolling interest in subsidiaries	0.1	0	0.1	0
Net income (loss) attributed to common shareholders	$ (5.4)	$ 48.8	$ 182.1	$ 147.7
Average shares of common stock
Basic (in shares)	79.4	78.5	79.0	78.5
Diluted (in shares)	79.4	79.3	79.7	79.3
Earnings (loss) per common share (basic)
Net income (loss) from continuing operations (in dollars per share)	$ (0.06)	$ 0.65	$ 2.24	$ 1.90
Discontinued operations, net of tax (in dollars per share)	$ (0.01)	$ (0.03)	$ 0.07	$ (0.02)
Earnings (loss) per common share (basic) (in dollars per share)	$ (0.07)	$ 0.62	$ 2.31	$ 1.88
Earnings (loss) per common share (diluted)
Net income (loss) from continuing operations (in dollars per share)	$ (0.06)	$ 0.65	$ 2.22	$ 1.88
Discontinued operations, net of tax (in dollars per share)	$ (0.01)	$ (0.03)	$ 0.07	$ (0.02)
Earnings (loss) per common share (diluted) (in dollars per share)	$ (0.07)	$ 0.62	$ 2.29	$ 1.86
Dividends per common share declared (in dollars per share)	$ 0.68	$ 0.68	$ 1.36	$ 1.36