Disaggregation of Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 3,669	$ 3,416	$ 3,648
IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,063	1,947	2,089
WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,523	1,395	1,476
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenues	3,081	2,920	3,064
Electric [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,752	1,695	1,781
Electric [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,329	1,225	1,283
Electric [Member] | Retail - Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,115	1,093	1,092
Electric [Member] | Retail - Residential [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	620	602	601
Electric [Member] | Retail - Residential [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	495	491	491
Electric [Member] | Retail - Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues	763	718	770
Electric [Member] | Retail - Commercial [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	508	474	510
Electric [Member] | Retail - Commercial [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	255	244	260
Electric [Member] | Retail - Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues	893	841	889
Electric [Member] | Retail - Industrial [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	505	488	504
Electric [Member] | Retail - Industrial [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	388	353	385
Electric [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenues	187	168	177
Electric [Member] | Wholesale [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	57	57	64
Electric [Member] | Wholesale [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	130	111	113
Electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenues	123	100	136
Electric [Member] | Other [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	62	74	102
Electric [Member] | Other [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	61	26	34
Gas [Member]
Disaggregation of Revenue [Line Items]
Revenues	456	373	455
Gas [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	265	208	264
Gas [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	191	165	191
Gas [Member] | Retail - Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	257	214	259
Gas [Member] | Retail - Residential [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	146	116	149
Gas [Member] | Retail - Residential [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	111	98	110
Gas [Member] | Retail - Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues	139	107	133
Gas [Member] | Retail - Commercial [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	79	59	75
Gas [Member] | Retail - Commercial [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	60	48	58
Gas [Member] | Retail - Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues	17	12	16
Gas [Member] | Retail - Industrial [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	12	8	12
Gas [Member] | Retail - Industrial [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	5	4	4
Gas [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenues	43	40	47
Gas [Member] | Other [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	28	25	28
Gas [Member] | Other [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	15	15	19
Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenues	49	49	46
Other Utility [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	46	44	44
Other Utility [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	3	5	2
Other Utility [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenues	13	13	9
Other Utility [Member] | Other [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	10	8	7
Other Utility [Member] | Other [Member] | WPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	3	5	2
Other Utility [Member] | Steam [Member]
Disaggregation of Revenue [Line Items]
Revenues	36	36	37
Other Utility [Member] | Steam [Member] | IPL [Member]
Disaggregation of Revenue [Line Items]
Revenues	36	36	37
Non-Utility and Other [Member]
Disaggregation of Revenue [Line Items]
Revenues	83	74	83
Non-Utility and Other [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 83	$ 74	$ 83