Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Carrying Amount [Member]
Assets:
Money market fund investments	$ 73	$ 45
Deferred proceeds	171	216
Liabilities:
Long-term debt (incl. current maturities)	9,704	9,034
Carrying Amount [Member] | IPL [Member]
Assets:
Money market fund investments	1	45
Deferred proceeds	171	216
Liabilities:
Long-term debt (incl. current maturities)	3,946	3,945
Carrying Amount [Member] | WPL [Member]
Assets:
Money market fund investments	72	0
Liabilities:
Long-term debt (incl. current maturities)	3,368	3,070
Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	103	88
Liabilities:
Derivatives	91	98
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	72	54
Liabilities:
Derivatives	31	30
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	31	34
Liabilities:
Derivatives	60	68
Carrying Amount [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	3	1
Money market fund investments	73	45
Deferred proceeds	171	216
Liabilities:
Long-term debt (incl. current maturities)	9,352	8,677
IPL [Member]
Assets:
Money market fund investments	1	45
Deferred proceeds	171	216
Liabilities:
Long-term debt (incl. current maturities)	3,577	3,664
WPL [Member]
Assets:
Money market fund investments	72	0
Liabilities:
Long-term debt (incl. current maturities)	3,141	2,933
Commodity Contracts [Member]
Assets:
Derivatives	103	88
Liabilities:
Derivatives	91	98
Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	72	54
Liabilities:
Derivatives	31	30
Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	31	34
Liabilities:
Derivatives	60	68
Interest Rate Swap [Member]
Assets:
Derivatives	3	1
Level 1 [Member]
Assets:
Money market fund investments	73	45
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | IPL [Member]
Assets:
Money market fund investments	1	45
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | WPL [Member]
Assets:
Money market fund investments	72	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 1 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 1 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 1 [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	0	0
Level 2 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	9,352	8,677
Level 2 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	3,577	3,664
Level 2 [Member] | WPL [Member]
Assets:
Money market fund investments	0	0
Liabilities:
Long-term debt (incl. current maturities)	3,141	2,933
Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	46	59
Liabilities:
Derivatives	85	93
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	26	30
Liabilities:
Derivatives	25	25
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	20	29
Liabilities:
Derivatives	60	68
Level 2 [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	3	1
Level 3 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	171	216
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	171	216
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | WPL [Member]
Assets:
Money market fund investments	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	57	29
Liabilities:
Derivatives	6	5
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	46	24
Liabilities:
Derivatives	6	5
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	11	5
Liabilities:
Derivatives	0	0
Level 3 [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	$ 0	$ 0