Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Assets:
Money market fund investments	$ 9	$ 32
Deferred proceeds	244	214
Liabilities:
Long-term debt (incl. current maturities)	7,403	8,330
IPL [Member]
Assets:
Money market fund investments	9	32
Deferred proceeds	244	214
Liabilities:
Long-term debt (incl. current maturities)	3,445	4,124
WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	2,370	2,862
Commodity Contracts [Member]
Assets:
Derivatives	359	176
Liabilities:
Derivatives	95	9
Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	207	84
Liabilities:
Derivatives	67	4
Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	152	92
Liabilities:
Derivatives	28	5
Level 1 [Member]
Assets:
Money market fund investments	9	32
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | IPL [Member]
Assets:
Money market fund investments	9	32
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | WPL [Member]
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 2 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	7,402	8,329
Level 2 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	3,445	4,124
Level 2 [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	2,370	2,862
Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	272	146
Liabilities:
Derivatives	80	8
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	138	65
Liabilities:
Derivatives	56	3
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	134	81
Liabilities:
Derivatives	24	5
Level 3 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	244	214
Liabilities:
Long-term debt (incl. current maturities)	1	1
Level 3 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	244	214
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	87	30
Liabilities:
Derivatives	15	1
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	69	19
Liabilities:
Derivatives	11	1
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	18	11
Liabilities:
Derivatives	4	0
Carrying Amount [Member]
Assets:
Money market fund investments	9	32
Deferred proceeds	244	214
Liabilities:
Long-term debt (incl. current maturities)	7,714	7,368
Carrying Amount [Member] | IPL [Member]
Assets:
Money market fund investments	9	32
Deferred proceeds	244	214
Liabilities:
Long-term debt (incl. current maturities)	3,645	3,643
Carrying Amount [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	2,430	2,429
Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	359	176
Liabilities:
Derivatives	95	9
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	207	84
Liabilities:
Derivatives	67	4
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	152	92
Liabilities:
Derivatives	$ 28	$ 5