Fair Value Measurements (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Carrying Amount [Member]
Assets:
Money market fund investments	$ 45	$ 10
Deferred proceeds	216	185
Liabilities and equity:
Long-term debt (including current maturities)	9,034	8,076
Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	88	237
Liabilities and equity:
Derivatives	98	79
Carrying Amount [Member] | Interest Rate Swap
Assets:
Derivatives	1	0
Money market fund investments	45	10
Deferred proceeds	216	185
Liabilities and equity:
Long-Term Debt, Fair Value	8,677	7,339
Commodity Contracts [Member]
Assets:
Derivatives	88	237
Liabilities and equity:
Derivatives	98	79
Interest Rate Swap
Assets:
Derivatives	1	0
Level 1 [Member]
Assets:
Money market fund investments	45	10
Deferred proceeds	0	0
Liabilities and equity:
Long-Term Debt, Fair Value	0	0
Level 1 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	0	0
Liabilities and equity:
Derivatives	0	0
Level 1 [Member] | Interest Rate Swap
Assets:
Derivatives	0	0
Level 2 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities and equity:
Long-Term Debt, Fair Value	8,677	7,338
Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	59	206
Liabilities and equity:
Derivatives	93	67
Level 2 [Member] | Interest Rate Swap
Assets:
Derivatives	1	0
Level 3 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	216	185
Liabilities and equity:
Long-Term Debt, Fair Value	0	1
Level 3 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	29	31
Liabilities and equity:
Derivatives	5	12
Level 3 [Member] | Interest Rate Swap
Assets:
Derivatives	0	0
IPL [Member] | Carrying Amount [Member]
Assets:
Money market fund investments	45	10
Deferred proceeds	216	185
Liabilities and equity:
Long-term debt (including current maturities)	3,945	3,646
IPL [Member] | Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	54	138
Liabilities and equity:
Derivatives	30	46
IPL [Member]
Assets:
Money market fund investments	45	10
Deferred proceeds	216	185
Liabilities and equity:
Long-Term Debt, Fair Value	3,664	3,228
IPL [Member] | Commodity Contracts [Member]
Assets:
Derivatives	54	138
Liabilities and equity:
Derivatives	30	46
IPL [Member] | Level 1 [Member]
Assets:
Money market fund investments	45	10
Deferred proceeds	0	0
Liabilities and equity:
Long-Term Debt, Fair Value	0	0
IPL [Member] | Level 1 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	0	0
Liabilities and equity:
Derivatives	0	0
IPL [Member] | Level 2 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities and equity:
Long-Term Debt, Fair Value	3,664	3,228
IPL [Member] | Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	30	111
Liabilities and equity:
Derivatives	25	35
IPL [Member] | Level 3 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	216	185
Liabilities and equity:
Long-Term Debt, Fair Value	0	0
IPL [Member] | Level 3 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	24	27
Liabilities and equity:
Derivatives	5	11
WPL [Member] | Carrying Amount [Member]
Liabilities and equity:
Long-term debt (including current maturities)	3,070	2,770
WPL [Member] | Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	34	99
Liabilities and equity:
Derivatives	68	33
WPL [Member]
Liabilities and equity:
Long-Term Debt, Fair Value	2,933	2,542
WPL [Member] | Commodity Contracts [Member]
Assets:
Derivatives	34	99
Liabilities and equity:
Derivatives	68	33
WPL [Member] | Level 1 [Member]
Liabilities and equity:
Long-Term Debt, Fair Value	0	0
WPL [Member] | Level 1 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	0	0
Liabilities and equity:
Derivatives	0	0
WPL [Member] | Level 2 [Member]
Liabilities and equity:
Long-Term Debt, Fair Value	2,933	2,542
WPL [Member] | Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	29	95
Liabilities and equity:
Derivatives	68	32
WPL [Member] | Level 3 [Member]
Liabilities and equity:
Long-Term Debt, Fair Value	0	0
WPL [Member] | Level 3 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	5	4
Liabilities and equity:
Derivatives	$ 0	$ 1