Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from (used for) operating activities:
Net income	$ 174	$ 173
Adjustments to reconcile net income to net cash flows from (used for) operating activities:
Depreciation and amortization	164	146
Deferred tax benefit and tax credits	(29)	(23)
Other	4	5
Other changes in assets and liabilities:
Accounts receivable	(126)	(119)
Regulatory liabilities	(60)	(38)
Deferred income taxes	58	50
Pension and other benefit obligations	(16)	(31)
Other	(24)	(3)
Net cash flows from (used for) operating activities	145	160
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(214)	(278)
Other construction and acquisition expenditures	(17)	(11)
Cash receipts on sold receivables	209	123
Other	(16)	(13)
Net cash flows from (used for) investing activities	(38)	(179)
Cash flows from (used for) financing activities:
Common stock dividends	(102)	(93)
Proceeds from issuance of common stock, net	8	228
Proceeds from issuance of long-term debt	0	300
Payments to retire long-term debt	0	(300)
Net change in commercial paper and other short-term borrowings	(53)	(67)
Other	2	(8)
Net cash flows from (used for) financing activities	(145)	60
Net increase (decrease) in cash, cash equivalents and restricted cash	(38)	41
Cash, cash equivalents and restricted cash at beginning of period	56	18
Cash, cash equivalents and restricted cash at end of period	18	59
Supplemental cash flows information:
Interest	(59)	(65)
Significant non-cash investing and financing activities:
Accrued capital expenditures	64	156
Beneficial interest obtained in exchange for securitized accounts receivable	107	188
IPL [Member]
Cash flows from (used for) operating activities:
Net income	82	86
Adjustments to reconcile net income to net cash flows from (used for) operating activities:
Depreciation and amortization	94	86
Other	(3)	(15)
Other changes in assets and liabilities:
Accounts receivable	(133)	(126)
Regulatory assets	(16)	(9)
Regulatory liabilities	(19)	1
Deferred income taxes	14	15
Other	(64)	(13)
Net cash flows from (used for) operating activities	(45)	25
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(106)	(165)
Cash receipts on sold receivables	209	123
Other	(5)	(11)
Net cash flows from (used for) investing activities	98	(53)
Cash flows from (used for) financing activities:
Common stock dividends	(101)	(60)
Capital contributions from parent	0	100
Other	9	4
Net cash flows from (used for) financing activities	(92)	44
Net increase (decrease) in cash, cash equivalents and restricted cash	(39)	16
Cash, cash equivalents and restricted cash at beginning of period	50	9
Cash, cash equivalents and restricted cash at end of period	11	25
Supplemental cash flows information:
Interest	(37)	(41)
Income taxes, net	7	0
Significant non-cash investing and financing activities:
Accrued capital expenditures	31	92
Beneficial interest obtained in exchange for securitized accounts receivable	107	188
WPL [Member]
Cash flows from (used for) operating activities:
Net income	84	90
Adjustments to reconcile net income to net cash flows from (used for) operating activities:
Depreciation and amortization	69	59
Deferred tax benefit and tax credits	(28)	(11)
Other	4	(5)
Other changes in assets and liabilities:
Regulatory liabilities	(41)	(39)
Deferred income taxes	44	32
Other	16	22
Net cash flows from (used for) operating activities	148	148
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(108)	(113)
Other	(11)	(11)
Net cash flows from (used for) investing activities	(119)	(124)
Cash flows from (used for) financing activities:
Common stock dividends	(42)	(43)
Capital contributions from parent	125	25
Net change in commercial paper and other short-term borrowings	(109)	14
Other	(4)	(1)
Net cash flows from (used for) financing activities	(30)	(5)
Net increase (decrease) in cash, cash equivalents and restricted cash	(1)	19
Cash, cash equivalents and restricted cash at beginning of period	3	4
Cash, cash equivalents and restricted cash at end of period	2	23
Supplemental cash flows information:
Interest	(21)	(21)
Significant non-cash investing and financing activities:
Accrued capital expenditures	$ 32	$ 62