Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Subsequent Event (Narrative) (Details) - USD ($) $ in Millions	Oct. 01, 2021	Sep. 30, 2021
Subsequent Event [Line Items]
Plant and Equipment associated with Schahfer Generating Station Retirement		$ 831.8
Subsequent Event \| Units 14 and 15
Subsequent Event [Line Items]
Plant and Equipment associated with Schahfer Generating Station Retirement	$ 600.0