CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating Activities
Net income	$ 772.0	$ 745.5
Reconciliation to cash provided by operating activities
Depreciation and amortization	593.5	581.5
Deferred income taxes and investment tax credits, net	444.4	439.5
Contributions and payments related to pension and OPEB plans	(115.4)	(23.5)
Equity income in transmission affiliate, net of distributions	(18.5)	(35.8)
Change in -
Accounts receivable and unbilled revenues	310.5	185.2
Materials, supplies, and inventories	(84.1)	33.8
Other current assets	57.9	88.5
Accounts payable	(111.2)	(94.7)
Other current liabilities	23.4	(92.9)
Other, net	(125.8)	(105.2)
Net cash provided by operating activities	1,746.7	1,721.9
Investing Activities
Capital expenditures	(1,309.2)	(1,000.1)
Acquisition of Bluewater	(226.0)	0.0
Capital contributions to transmission affiliate	(63.3)	(27.1)
Proceeds from the sale of assets and businesses	22.7	161.2
Withdrawal of restricted cash from rabbi trust for qualifying payments	18.7	23.8
Other, net	5.1	0.6
Net cash used in investing activities	(1,552.0)	(841.6)
Financing Activities
Exercise of stock options	25.6	40.4
Purchase of common stock	(60.6)	(105.6)
Dividends paid on common stock	(492.4)	(468.6)
Issuance of long-term debt	210.0	200.0
Retirement of long-term debt	(26.9)	(253.5)
Change in short-term debt	133.3	(305.6)
Other, net	(3.1)	(12.2)
Net cash used in financing activities	(214.1)	(905.1)
Net change in cash and cash equivalents	(19.4)	(24.8)
Cash and cash equivalents at beginning of period	37.5	49.8
Cash and cash equivalents at end of period	$ 18.1	$ 25.0