Regulatory Matters (Schedule of COVID-19 Regulatory Impact) (Details) - USD ($)	Dec. 31, 2025	Sep. 30, 2025	Dec. 31, 2024
Regulatory Matters COVID [Line Items]
COVID-19 related regulatory asset	$ 2,499,400,000	$ 5.7	$ 2,477,300,000

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
-Topic 980
-SubTopic 340
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478742/980-340-50-1

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