Leases (Expected Maturities of Operating and Finance Lease Liabilities (Details) $ in Millions	Dec. 31, 2019 USD ($)
Leases [Line Items]
Operating Leases Liability, 2020	$ 2
Operating Leases Liability, 2021	2
Operating Leases Liability, 2022	2
Operating Leases Liability, 2023	2
Operating Leases Liability, 2024	2
Operating Leases Liability, Thereafter	10
Operating Leases Liability, Total	20
Operating Leases Liability, Less: amount representing interest	4
Operating Leases Liability, Present value of minimum lease payments	16
IPL [Member]
Leases [Line Items]
Operating Leases Liability, 2020	1
Operating Leases Liability, 2021	1
Operating Leases Liability, 2022	1
Operating Leases Liability, 2023	1
Operating Leases Liability, 2024	1
Operating Leases Liability, Thereafter	7
Operating Leases Liability, Total	12
Operating Leases Liability, Less: amount representing interest	2
Operating Leases Liability, Present value of minimum lease payments	10
WPL [Member]
Leases [Line Items]
Operating Leases Liability, 2020	1
Operating Leases Liability, 2021	1
Operating Leases Liability, 2022	1
Operating Leases Liability, 2023	1
Operating Leases Liability, 2024	1
Operating Leases Liability, Thereafter	3
Operating Leases Liability, Total	8
Operating Leases Liability, Less: amount representing interest	2
Operating Leases Liability, Present value of minimum lease payments	6
Sheboygan Falls Energy Facility [Member] | WPL [Member]
Leases [Line Items]
Finance Lease Liability, 2020	15
Finance Lease Liability, 2021	15
Finance Lease Liability, 2022	15
Finance Lease Liability, 2023	15
Finance Lease Liability, 2024	15
Finance Lease Liability, Thereafter	5
Finance Lease Liability, Total	80
Finance Lease Liability, Less: amount representing interest	20
Finance Lease Liability, Present value of minimum lease payments	$ 60