Leases (Finance Lease) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Line Items]
Finance lease assets, Property, plant and equipment, net	$ 11
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other	Other
Finance lease liabilities, Other current liabilities	$ 1
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other	Other
Finance lease liabilities, Other liabilities	$ 11
Finance lease liabilities, Total	$ 12
Finance lease, Weighted average remaining lease term	34 years
Finance lease, Weighted average discount rate, percent	3.00%
Finance lease, Depreciation and amortization expense	$ 0
Finance lease, Interest expense	0
Finance lease, Total expense	$ 0
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
Leased land for solar generation [Member]
Leases [Line Items]
Finance lease assets, Property, plant and equipment, net	$ 11
Finance lease liabilities, Other current liabilities	1
Finance lease liabilities, Other liabilities	11
WPL [Member]
Leases [Line Items]
Finance lease assets, Property, plant and equipment, net	32	$ 27
Finance lease liabilities, Other current liabilities	11	9
Finance lease liabilities, Other liabilities	42	42
Finance lease liabilities, Total	$ 53	$ 51
Finance lease, Weighted average remaining lease term	10 years	4 years
Finance lease, Weighted average discount rate, percent	9.00%	11.00%
Finance lease, Depreciation and amortization expense	$ 6	$ 6	$ 6
Finance lease, Interest expense	5	6	7
Finance lease, Total expense	11	12	$ 13
WPL [Member] | Sheboygan Falls Energy Facility [Member]
Leases [Line Items]
Finance lease assets, Property, plant and equipment, net	21	27
Finance lease liabilities, Other current liabilities	10	9
Finance lease liabilities, Other liabilities	31	42
WPL [Member] | Leased land for solar generation [Member]
Leases [Line Items]
Finance lease assets, Property, plant and equipment, net	11	0
Finance lease liabilities, Other current liabilities	1	0
Finance lease liabilities, Other liabilities	$ 11	$ 0