Leases (Expected Maturities of Operating and Finance Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Leases [Line Items]
Operating Leases Liability, 2024	$ 3
Operating Leases Liability, 2025	3
Operating Leases Liability, 2026	3
Operating Leases Liability, 2027	3
Operating Leases Liability, 2028	2
Operating Leases Liability, Thereafter	16
Operating Leases Liability, Total	30
Operating Leases Liability, Less: amount representing interest	7
Operating Leases Liability, Present value of minimum lease payments	23	$ 16
Finance Lease Liability, 2024	8
Finance Lease Liability, 2025	8
Finance Lease Liability, 2026	8
Finance Lease Liability, 2027	8
Finance Lease Liability, 2028	8
Finance Lease Liability, Thereafter	320
Finance Lease Liability, Total	360
Finance Lease Liability, Less: amount representing interest	188
Finance Lease Liability, Present value of minimum lease payments	172	136
IPL [Member]
Leases [Line Items]
Operating Leases Liability, 2024	1
Operating Leases Liability, 2025	2
Operating Leases Liability, 2026	2
Operating Leases Liability, 2027	1
Operating Leases Liability, 2028	1
Operating Leases Liability, Thereafter	10
Operating Leases Liability, Total	17
Operating Leases Liability, Less: amount representing interest	4
Operating Leases Liability, Present value of minimum lease payments	13	9
Finance Lease Liability, 2024	2
Finance Lease Liability, 2025	2
Finance Lease Liability, 2026	2
Finance Lease Liability, 2027	2
Finance Lease Liability, 2028	2
Finance Lease Liability, Thereafter	59
Finance Lease Liability, Total	69
Finance Lease Liability, Less: amount representing interest	36
Finance Lease Liability, Present value of minimum lease payments	33	0
WPL [Member]
Leases [Line Items]
Operating Leases Liability, 2024	2
Operating Leases Liability, 2025	1
Operating Leases Liability, 2026	1
Operating Leases Liability, 2027	1
Operating Leases Liability, 2028	1
Operating Leases Liability, Thereafter	6
Operating Leases Liability, Total	12
Operating Leases Liability, Less: amount representing interest	3
Operating Leases Liability, Present value of minimum lease payments	9	6
Finance Lease Liability, 2024	21
Finance Lease Liability, 2025	17
Finance Lease Liability, 2026	13
Finance Lease Liability, 2027	13
Finance Lease Liability, 2028	13
Finance Lease Liability, Thereafter	334
Finance Lease Liability, Total	411
Finance Lease Liability, Less: amount representing interest	183
Finance Lease Liability, Present value of minimum lease payments	$ 228	$ 167