Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net income	$ 1,134.7	$ 1,060.5	$ 1,204.9
Reconciliation to cash provided by operating activities
Depreciation and amortization	926.3	845.8	798.6
Deferred income taxes and investment tax credits, net	162.9	297.3	271.7
Contributions and payments related to pension and OPEB plans	(65.9)	(77.6)	(120.5)
Equity income in transmission affiliate, net of distributions	(2.9)	(18.6)	(4.8)
Change in -
Accounts receivable and unbilled revenues	98.2	23.5	(86.4)
Materials, supplies, and inventories	(1.5)	(8.8)	49.3
Other current assets	(7.1)	(10.0)	(7.1)
Accounts payable	1.5	110.6	8.5
Other current liabilities	78.7	(67.6)	161.8
Other, net	20.6	290.4	(197.4)
Net cash provided by operating activities	2,345.5	2,445.5	2,078.6
Investing Activities
Capital expenditures	(2,260.8)	(2,115.7)	(1,959.5)
Acquisition of Upstream, net of cash and restricted cash acquired of $9.2 million	(268.2)	0.0	0.0
Acquisition of Bishop Hill III, net of restricted cash acquired of $4.5 million	0.0	(162.9)	0.0
Acquisition of Forward Wind Energy Center	0.0	(77.1)	0.0
Acquisition of Coyote Ridge	0.0	(61.4)	0.0
Acquisition of Bluewater	0.0	0.0	(226.0)
Capital contributions to transmission affiliates	(52.6)	(53.5)	(109.6)
Proceeds from the sale of assets and businesses	37.6	12.1	24.0
Proceeds from the sale of investments held in rabbi trust	0.2	118.6	8.7
Purchase of investments held in rabbi trust	0.0	(65.0)	(3.7)
Reimbursement for ATC's construction costs	32.4	0.0	0.0
Other, net	16.5	20.5	12.0
Net cash used in investing activities	(2,494.9)	(2,384.4)	(2,254.1)
Financing Activities
Exercise of stock options	67.0	29.1	30.8
Purchase of common stock	(140.1)	(72.4)	(71.3)
Dividends paid on common stock	(744.5)	(697.3)	(656.5)
Issuance of long-term debt	1,895.0	1,740.0	435.0
Retirement of long-term debt	(360.1)	(953.3)	(154.5)
Change in short-term debt	(609.3)	(4.5)	584.4
Other, net	(22.4)	(15.2)	(6.5)
Net cash provided by financing activities	85.6	26.4	161.4
Net change in cash, cash equivalents, and restricted cash	(63.8)	87.5	(14.1)
Cash, cash equivalents, and restricted cash at beginning of year	146.1	58.6	72.7
Cash, cash equivalents, and restricted cash at end of year	$ 82.3	$ 146.1	$ 58.6