Consolidated Condensed Income Statements (Unaudited) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating Revenues	$ 1,275.2	$ 1,191.2
Operating Expenses
Fuel and purchased power	271.0	253.8
Cost of gas sold	270.1	237.5
Other operation and maintenance	288.1	286.3
Depreciation and amortization	95.5	87.6
Property and revenue taxes	29.5	30.3
Total Operating Expenses	954.2	895.5
Operating Income	321.0	295.7
Income (Loss) from Equity Method Investments	16.7	15.6
Other Income, net	4.4	16.0
Interest Expense, net	65.0	58.9
Income from Continuing Operations Before Income Taxes	277.0	268.4
Income Tax Expense	100.4	96.3
Net Income	176.6	172.1
Earnings Per Share (Basic)
Continuing operations	$ 0.77	$ 0.75
Earnings Per Share (Diluted)
Continuing operations	$ 0.76	$ 0.74
Weighted Average Common Shares Outstanding (Millions)
Basic	228.9	230.5
Diluted	231.2	233.2
Dividends Per Share of Common Stock	$ 0.34	$ 0.30
Transmission Affiliate [Member]
Operating Expenses
Income (Loss) from Equity Method Investments	$ 16.6	$ 15.6