Regulatory Environment - PGL QIP Rider (Details) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) Assurance	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Aug. 31, 2024 USD ($)
Public Utilities, General Disclosures
Pre-tax charge to income		$ (1,746.3)	$ (1,536.3)	$ (1,732.6)
Reduction in revenues		(8,599.9)	(8,893.0)	(9,597.4)
Other operation and maintenance		2,158.0	2,100.5	1,938.0
Interest expense		815.3	$ 727.4	$ 515.1
PGL
Public Utilities, General Disclosures
Other operation and maintenance	$ 12.1
Illinois Commerce Commission (ICC) | PGL | 2016 Annual QIP Rider Reconciliation
Public Utilities, General Disclosures
Disallowed capital costs					$ 14.8
Pre-tax charge to income	25.3
Reduction in revenues	12.9
Other operation and maintenance	12.1
Interest expense	$ 0.3
Illinois Commerce Commission (ICC) | PGL | Open Rider QIP Reconciliations
Public Utilities, General Disclosures
Aggregate capital costs during open reconciliation years		$ 2,800.0
Amount of assurance that PGL's QIP rider costs will be recoverable | Assurance		0