Preferred Stock (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Temporary Equity [Line Items]
Payments to redeem cumulative preferred stock of IPL	$ 200	$ 0	$ 0
Cumulative Preferred Stock [Member] | 5.1% [Member]
Temporary Equity [Line Items]
Non-cash charge, preferred stock redemption	5
IPL [Member]
Temporary Equity [Line Items]
Payments to redeem cumulative preferred stock of IPL	$ 200	$ 0	$ 0
IPL [Member] | Cumulative Preferred Stock [Member]
Temporary Equity [Line Items]
Shares authorized (in shares)	16,000,000
IPL [Member] | Cumulative Preferred Stock [Member] | 5.1% [Member]
Temporary Equity [Line Items]
Shares authorized (in shares)		8,000,000
Shares outstanding (in shares)		8,000,000
Cumulative preferred stock rate		5.10%
Preferred stock redemption price per share (in dollars per share)		$ 25
Payments to redeem cumulative preferred stock of IPL	$ 200
Non-cash charge, preferred stock redemption	$ 5