Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 224.8	$ 226.4
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	279.8	247.4
Deferred tax expense (benefit) and tax credits	19.9	33.9
Equity component of allowance for funds used during construction	(30.8)	(22.6)
Equity income from unconsolidated investments, net	(23.6)	(31.8)
Other	37.1	31.6
Other changes in assets and liabilities:
Accounts receivable	(199.7)	(168.4)
Accounts payable	(33.1)	(34.1)
Regulatory liabilities	(26.1)	21.5
Deferred income taxes	34.3	(6.3)
Other	(5.7)	(23.2)
Net cash flows from operating activities	276.9	274.4
Cash flows used for investing activities:
Utility business construction and acquisition expenditures	(652.5)	(699.6)
Other construction and acquisition expenditures	(54.1)	(33.7)
Cash receipts on sold receivables	125.5	232.5
Other	(25.9)	(17.1)
Net cash flows used for investing activities	(607.0)	(517.9)
Cash flows from financing activities:
Common stock dividends	(167.8)	(154.8)
Proceeds from issuance of common stock, net	60.6	100.1
Proceeds from issuance of long-term debt	650.0	1,000.0
Payments to retire long-term debt	(3.4)	(503.0)
Net change in commercial paper and other short-term borrowings	(50.7)	(207.7)
Other	(9.9)	(13.0)
Net cash flows from financing activities	478.8	221.6
Net increase (decrease) in cash, cash equivalents and restricted cash	148.7	(21.9)
Cash, cash equivalents and restricted cash at beginning of period	25.5	33.9
Cash, cash equivalents and restricted cash at end of period	174.2	12.0
Supplemental cash flows information:
Interest	(132.7)	(119.8)
Income taxes, net	2.5	(5.0)
Significant non-cash investing and financing activities:
Accrued capital expenditures	187.4	186.5
Beneficial interest obtained in exchange for securitized accounts receivable	214.6	208.3
IPL [Member]
Cash flows from operating activities:
Net income	103.4	103.5
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	159.7	135.3
Deferred tax expense (benefit) and tax credits	(11.7)	9.6
Other	(14.9)	(10.3)
Other changes in assets and liabilities:
Accounts receivable	(209.3)	(206.2)
Accounts payable	(17.0)	(29.3)
Accrued taxes	18.9	(2.1)
Deferred income taxes	25.3	(17.8)
Other	34.6	30.1
Net cash flows from operating activities	89.0	12.8
Cash flows used for investing activities:
Utility business construction and acquisition expenditures	(449.5)	(391.1)
Cash receipts on sold receivables	125.5	232.5
Other	(30.5)	(20.5)
Net cash flows used for investing activities	(354.5)	(179.1)
Cash flows from financing activities:
Common stock dividends	(83.9)	(84.0)
Capital contributions from parent	100.0	130.0
Proceeds from issuance of long-term debt	300.0	0.0
Net change in commercial paper and other short-term borrowings	(50.4)	125.0
Other	(6.2)	(6.6)
Net cash flows from financing activities	259.5	164.4
Net increase (decrease) in cash, cash equivalents and restricted cash	(6.0)	(1.9)
Cash, cash equivalents and restricted cash at beginning of period	12.4	7.2
Cash, cash equivalents and restricted cash at end of period	6.4	5.3
Supplemental cash flows information:
Interest	(58.3)	(60.2)
Income taxes, net	12.1	(0.5)
Significant non-cash investing and financing activities:
Accrued capital expenditures	117.4	93.4
Beneficial interest obtained in exchange for securitized accounts receivable	214.6	208.3
WPL [Member]
Cash flows from operating activities:
Net income	107.7	93.8
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	117.7	110.1
Deferred tax expense (benefit) and tax credits	21.7	14.5
Other	(4.7)	(8.1)
Other changes in assets and liabilities:
Accounts receivable	7.6	39.0
Accounts payable	(19.6)	(10.4)
Regulatory liabilities	(18.4)	2.5
Other	(3.8)	(15.5)
Net cash flows from operating activities	208.2	225.9
Cash flows used for investing activities:
Utility business construction and acquisition expenditures	(203.0)	(308.5)
Other	(15.0)	(17.0)
Net cash flows used for investing activities	(218.0)	(325.5)
Cash flows from financing activities:
Common stock dividends	(72.0)	(70.1)
Capital contributions from parent	0.0	150.0
Proceeds from issuance of long-term debt	350.0	0.0
Net change in commercial paper and other short-term borrowings	(105.5)	1.4
Other	(7.4)	(1.3)
Net cash flows from financing activities	165.1	80.0
Net increase (decrease) in cash, cash equivalents and restricted cash	155.3	(19.6)
Cash, cash equivalents and restricted cash at beginning of period	9.2	24.2
Cash, cash equivalents and restricted cash at end of period	164.5	4.6
Supplemental cash flows information:
Interest	(51.7)	(49.4)
Income taxes, net	(6.5)	(7.9)
Significant non-cash investing and financing activities:
Accrued capital expenditures	$ 66.4	$ 89.6