Leases (Operating Leases) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Line Items]
Operating leases assets, Property, plant and equipment, net	$ 16
Operating leases liabilities, Other current liabilities	2
Operating leases liabilities, Other liabilities	14
Operating leases liabilities, Total	$ 16
Operating leases, Weighted average remaining lease term	11 years
Operating leases, Weighted average discount rate, percent	4.00%
Operating leases, Cost	$ 2
IPL [Member]
Leases [Line Items]
Operating leases assets, Property, plant and equipment, net	10
Operating leases liabilities, Other current liabilities	1
Operating leases liabilities, Other liabilities	9
Operating leases liabilities, Total	$ 10
Operating leases, Weighted average remaining lease term	12 years
Operating leases, Weighted average discount rate, percent	4.00%
Operating leases, Cost	$ 1
WPL [Member]
Leases [Line Items]
Operating leases assets, Property, plant and equipment, net	6
Operating leases liabilities, Other current liabilities	1
Operating leases liabilities, Other liabilities	5
Operating leases liabilities, Total	$ 6
Operating leases, Weighted average remaining lease term	10 years
Operating leases, Weighted average discount rate, percent	4.00%
Operating leases, Cost	$ 1