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
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-Section 50
-Paragraph 7A
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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-Topic 944
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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	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Policyholder Account Balance [Line Items]
Policyholders' account balances	$ 5,041.8		$ 5,064.1
Indexed Universal Life
Policyholder Account Balance [Line Items]
Policyholders' account balances	107.9	$ 100.6	95.5	$ 82.3	$ 78.2	$ 72.9
Experience life
Policyholder Account Balance [Line Items]
Policyholders' account balances	52.8	53.7	54.8	56.5	57.4	58.0
Fixed Account Annuities
Policyholder Account Balance [Line Items]
Policyholders' account balances	4,469.0	4,482.6	4,486.8	4,495.1	4,495.9	4,508.4
Fixed Indexed Account Annuities
Policyholder Account Balance [Line Items]
Policyholders' account balances	360.7	365.1	373.3	388.6	399.7	409.5
SPIA (non-life contingent)
Policyholder Account Balance [Line Items]
Policyholders' account balances	25.8	$ 26.2	26.1	$ 27.9	$ 28.3	$ 28.6
Reconciling items
Policyholder Account Balance [Line Items]
Policyholders' account balances	$ 25.6		$ 27.6