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
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 29F
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-29F

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

Long-Duration Insurance Contracts - Reconciliation of Policyholder Account Balances to the Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2026	Jun. 30, 2026	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024
Policyholder Account Balance [Line Items]
Policyholders' account balances	$ 5,043.2		$ 5,064.1
Indexed Universal Life
Policyholder Account Balance [Line Items]
Policyholders' account balances	115.3	$ 108.0	95.5	$ 87.2	$ 82.3	$ 72.9
Experience life
Policyholder Account Balance [Line Items]
Policyholders' account balances	52.1	52.8	54.8	55.7	56.5	58.0
Fixed Account Annuities
Policyholder Account Balance [Line Items]
Policyholders' account balances	4,472.3	4,469.0	4,486.8	4,514.6	4,495.1	4,508.4
Fixed Indexed Account Annuities
Policyholder Account Balance [Line Items]
Policyholders' account balances	354.8	360.7	373.3	382.3	388.6	409.5
SPIA (non-life contingent)
Policyholder Account Balance [Line Items]
Policyholders' account balances	25.4	$ 25.8	26.1	$ 27.4	$ 27.9	$ 28.6
Reconciling items
Policyholder Account Balance [Line Items]
Policyholders' account balances	$ 23.3		$ 27.6