Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Subsection 04
-Paragraph a
-Publisher SEC

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-X (SX)
-Number 210
-Section 5
-Subsection 04
-Paragraph c
-Subparagraph Schedule I
-Publisher SEC

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-X (SX)
-Number 210
-Section 7
-Subsection 05
-Paragraph c
-Subparagraph Schedule II
-Publisher SEC

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-X (SX)
-Number 210
-Section 9
-Subsection 06
-Publisher SEC

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-3

Reference 6: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 810
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481231/810-10-45-11

Name:	srt_CondensedFinancialStatementsCaptionsLineItems
Namespace Prefix:	srt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Schedule I - Condensed Financial Information - Notes to Condensed Financial Statements (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 22, 2016
Parent Company and Unregulated Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Investments and cash	$ 151.5	$ 83.2
Regulated Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Investments and cash	$ 286.1	$ 280.5
Parent Company
Condensed Financial Statements, Captions [Line Items]
Surplus note			$ 40.0