Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Assets:
Money market fund investments	$ 6	$ 10
Deferred proceeds	175	185
Liabilities:
Long-term debt (incl. current maturities)	7,951	7,339
IPL [Member]
Assets:
Money market fund investments	6	10
Deferred proceeds	175	185
Liabilities:
Long-term debt (incl. current maturities)	3,321	3,228
WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	2,875	2,542
Commodity Contracts [Member]
Assets:
Derivatives	147	237
Liabilities:
Derivatives	97	79
Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	95	138
Liabilities:
Derivatives	37	46
Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	52	99
Liabilities:
Derivatives	60	33
Interest Rate Swap [Member]
Assets:
Derivatives	4	0
Level 1 [Member]
Assets:
Money market fund investments	6	10
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | IPL [Member]
Assets:
Money market fund investments	6	10
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 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)	7,950	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)	3,321	3,228
Level 2 [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	2,875	2,542
Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	80	206
Liabilities:
Derivatives	84	67
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	44	111
Liabilities:
Derivatives	27	35
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	36	95
Liabilities:
Derivatives	57	32
Level 2 [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	4	0
Level 3 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	175	185
Liabilities:
Long-term debt (incl. current maturities)	1	1
Level 3 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	175	185
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	67	31
Liabilities:
Derivatives	13	12
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	51	27
Liabilities:
Derivatives	10	11
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	16	4
Liabilities:
Derivatives	3	1
Level 3 [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	0	0
Carrying Amount [Member]
Assets:
Money market fund investments	6	10
Deferred proceeds	175	185
Liabilities:
Long-term debt (incl. current maturities)	8,595	8,076
Carrying Amount [Member] | IPL [Member]
Assets:
Money market fund investments	6	10
Deferred proceeds	175	185
Liabilities:
Long-term debt (incl. current maturities)	3,702	3,646
Carrying Amount [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	3,068	2,770
Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	147	237
Liabilities:
Derivatives	97	79
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	95	138
Liabilities:
Derivatives	37	46
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	52	99
Liabilities:
Derivatives	60	33
Carrying Amount [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	$ 4	$ 0