Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Regulatory Matters [Line Items]
Regulatory assets	$ 2,007	$ 2,010
IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	1,494	$ 1,483
Deferred Fuel Costs \| IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	$ 20

The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

Name:	us-gaap_RegulatoryAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant