Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Activities
Net income	$ 546.3	$ 526.2	$ 456.5
Reconciliation to cash
Depreciation and amortization	371.7	336.4	317.4
Amortization of gain	0	0	(198.4)
Deferred income taxes and investment tax credits, net	352.2	430.6	104.9
Deferred revenue	0	3.5	100.8
Contributions to qualified benefit plans	(100.0)	(277.4)	0
Change in -
Accounts receivable and accrued revenues	38.3	30.1	(50.4)
Inventories	21.3	(2.9)	(1.0)
Other current assets	12.1	(20.5)	14.1
Accounts payable	43.8	11.8	21.3
Accrued income taxes, net	57.9	(87.4)	(42.7)
Deferred costs, net	9.2	25.9	25.9
Other current liabilities	(14.9)	44.1	22.0
Other, net	(164.0)	(27.0)	40.0
Cash Provided by Operating Activities	1,173.9	993.4	810.4
Investing Activities
Capital expenditures	(707.0)	(830.8)	(798.2)
Investment in transmission affiliate	(15.7)	(6.6)	(5.2)
Proceeds from asset sales	8.7	41.5	68.7
Change in restricted cash	42.8	(37.2)	186.2
Other, net	(58.4)	(59.4)	(85.0)
Cash Used in Investing Activities	(729.6)	(892.5)	(633.5)
Financing Activities
Exercise of stock options	49.8	54.4	90.9
Purchase of common stock	(153.2)	(193.9)	(156.6)
Dividends paid on common stock	(276.3)	(242.0)	(187.0)
Issuance of long-term debt	251.8	720.0	530.0
Retirement and repurchase of long-term debt	(20.3)	(466.6)	(291.7)
Change in short-term debt	(275.3)	12.0	(167.2)
Other, net	0.7	4.8	9.0
Cash Used in Financing Activities	(422.8)	(111.3)	(172.6)
Change in Cash and Cash Equivalents	21.5	(10.4)	4.3
Cash and Cash Equivalents at Beginning of Year	14.1	24.5	20.2
Cash and Cash Equivalents at End of Year	$ 35.6	$ 14.1	$ 24.5