Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income	$ 579	$ 558
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	494	454
Deferred tax benefit and tax credits	(69)	(48)
Other	7	(17)
Other changes in assets and liabilities:
Accounts receivable	(397)	(316)
Derivative assets	(202)	(22)
Regulatory liabilities	25	(72)
Deferred income taxes	160	143
Pension and other benefit obligations	(59)	(61)
DAEC PPA amendment buyout payment	0	(110)
Other	(61)	(73)
Net cash flows from operating activities	477	436
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(772)	(935)
Other construction and acquisition expenditures	(60)	(39)
Cash receipts on sold receivables	423	318
Other	(43)	(23)
Net cash flows from (used for) investing activities	(452)	(679)
Cash flows from (used for) financing activities:
Common stock dividends	(304)	(281)
Proceeds from issuance of common stock, net	22	241
Proceeds from issuance of long-term debt	300	1,050
Payments to retire long-term debt	(4)	(654)
Net change in commercial paper	(73)	85
Other	2	(22)
Net cash flows from (used for) financing activities	(57)	419
Net increase (decrease) in cash, cash equivalents and restricted cash	(32)	176
Cash, cash equivalents and restricted cash at beginning of period	56	18
Cash, cash equivalents and restricted cash at end of period	24	194
Supplemental cash flows information:
Interest	(197)	(197)
Income taxes, net	(1)	6
Significant non-cash investing and financing activities:
Accrued capital expenditures	91	202
Beneficial interest obtained in exchange for securitized accounts receivable	164	201
IPL [Member]
Cash flows from operating activities:
Net income	330	298
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	281	264
Deferred tax benefit and tax credits	(13)	(42)
Other	(1)	(9)
Other changes in assets and liabilities:
Accounts receivable	(412)	(337)
Derivative assets	(86)	(12)
Regulatory assets	(33)	(32)
Regulatory liabilities	30	(11)
Deferred income taxes	56	62
Pension and other benefit obligations	(25)	(19)
DAEC PPA amendment buyout payment	0	(110)
Other	(32)	(33)
Net cash flows from operating activities	95	19
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(285)	(465)
Cash receipts on sold receivables	423	318
Other	(16)	(55)
Net cash flows from (used for) investing activities	122	(202)
Cash flows from (used for) financing activities:
Common stock dividends	(301)	(177)
Capital contributions from parent	50	345
Proceeds from issuance of long-term debt	0	400
Payments to retire long-term debt	0	(200)
Other	(3)	(9)
Net cash flows from (used for) financing activities	(254)	359
Net increase (decrease) in cash, cash equivalents and restricted cash	(37)	176
Cash, cash equivalents and restricted cash at beginning of period	50	9
Cash, cash equivalents and restricted cash at end of period	13	185
Supplemental cash flows information:
Interest	(106)	(109)
Income taxes, net	28	(12)
Significant non-cash investing and financing activities:
Accrued capital expenditures	30	150
Beneficial interest obtained in exchange for securitized accounts receivable	164	201
WPL [Member]
Cash flows from operating activities:
Net income	215	220
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	209	186
Deferred tax benefit and tax credits	(63)	(9)
Other	12	(8)
Other changes in assets and liabilities:
Derivative assets	(116)	(10)
Regulatory liabilities	(5)	(61)
Deferred income taxes	108	79
Other	(11)	5
Net cash flows from operating activities	349	402
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(487)	(470)
Other	(23)	5
Net cash flows from (used for) investing activities	(510)	(465)
Cash flows from (used for) financing activities:
Common stock dividends	(126)	(127)
Capital contributions from parent	245	25
Proceeds from issuance of long-term debt	300	350
Payments to retire long-term debt	0	(150)
Net change in commercial paper	(254)	(29)
Other	(3)	(8)
Net cash flows from (used for) financing activities	162	61
Net increase (decrease) in cash, cash equivalents and restricted cash	1	(2)
Cash, cash equivalents and restricted cash at beginning of period	3	4
Cash, cash equivalents and restricted cash at end of period	4	2
Supplemental cash flows information:
Interest	(72)	(71)
Income taxes, net	(24)	5
Significant non-cash investing and financing activities:
Accrued capital expenditures	$ 59	$ 50