Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Assets:
Money market fund investments	$ 148	$ 10
Deferred proceeds	153	185
Liabilities:
Long-term debt (incl. current maturities)	8,462	7,339
IPL [Member]
Assets:
Money market fund investments	30	10
Deferred proceeds	153	185
Liabilities:
Long-term debt (incl. current maturities)	3,335	3,228
WPL [Member]
Assets:
Money market fund investments	83	0
Liabilities:
Long-term debt (incl. current maturities)	2,939	2,542
Commodity Contracts [Member]
Assets:
Derivatives	122	237
Liabilities:
Derivatives	95	79
Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	69	138
Liabilities:
Derivatives	34	46
Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	53	99
Liabilities:
Derivatives	61	33
Interest Rate Swap [Member]
Liabilities:
Derivatives	1	0
Level 1 [Member]
Assets:
Money market fund investments	148	10
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | IPL [Member]
Assets:
Money market fund investments	30	10
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | WPL [Member]
Assets:
Money market fund investments	83	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]
Liabilities:
Derivatives	0	0
Level 2 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	8,461	7,338
Level 2 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	3,335	3,228
Level 2 [Member] | WPL [Member]
Assets:
Money market fund investments	0	0
Liabilities:
Long-term debt (incl. current maturities)	2,939	2,542
Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	116	206
Liabilities:
Derivatives	84	67
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	63	111
Liabilities:
Derivatives	28	35
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	53	95
Liabilities:
Derivatives	56	32
Level 2 [Member] | Interest Rate Swap [Member]
Liabilities:
Derivatives	1	0
Level 3 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	153	185
Liabilities:
Long-term debt (incl. current maturities)	1	1
Level 3 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	153	185
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	6	31
Liabilities:
Derivatives	11	12
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	6	27
Liabilities:
Derivatives	6	11
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	0	4
Liabilities:
Derivatives	5	1
Level 3 [Member] | Interest Rate Swap [Member]
Liabilities:
Derivatives	0	0
Carrying Amount [Member]
Assets:
Money market fund investments	148	10
Deferred proceeds	153	185
Liabilities:
Long-term debt (incl. current maturities)	8,940	8,076
Carrying Amount [Member] | IPL [Member]
Assets:
Money market fund investments	30	10
Deferred proceeds	153	185
Liabilities:
Long-term debt (incl. current maturities)	3,647	3,646
Carrying Amount [Member] | WPL [Member]
Assets:
Money market fund investments	83	0
Liabilities:
Long-term debt (incl. current maturities)	3,067	2,770
Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	122	237
Liabilities:
Derivatives	95	79
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	69	138
Liabilities:
Derivatives	34	46
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	53	99
Liabilities:
Derivatives	61	33
Carrying Amount [Member] | Interest Rate Swap [Member]
Liabilities:
Derivatives	$ 1	$ 0