Goodwill and Intangible Assets - Schedule of Future Amortization Expense (Details) $ in Millions	Dec. 31, 2024 USD ($)
Finite-Lived Intangible Assets [Line Items]
Definite-life intangible assets, amortization expense, year one	$ 46.1
Definite-life intangible assets, amortization expense, year two	41.4
Definite-life intangible assets, amortization expense, year three	32.0
Definite-life intangible assets, amortization expense, year four	28.6
Definite-life intangible assets, amortization expense, year five	21.1
Agent Relationships
Finite-Lived Intangible Assets [Line Items]
Definite-life intangible assets, amortization expense, year one	8.6
Definite-life intangible assets, amortization expense, year two	8.6
Definite-life intangible assets, amortization expense, year three	4.9
Definite-life intangible assets, amortization expense, year four	4.9
Definite-life intangible assets, amortization expense, year five	4.9
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Definite-life intangible assets, amortization expense, year one	0.4
Definite-life intangible assets, amortization expense, year two	0.4
Definite-life intangible assets, amortization expense, year three	0.3
Definite-life intangible assets, amortization expense, year four	0.2
Definite-life intangible assets, amortization expense, year five	0.2
Internal Use Software
Finite-Lived Intangible Assets [Line Items]
Definite-life intangible assets, amortization expense, year one	35.5
Definite-life intangible assets, amortization expense, year two	30.9
Definite-life intangible assets, amortization expense, year three	25.3
Definite-life intangible assets, amortization expense, year four	22.1
Definite-life intangible assets, amortization expense, year five	14.7
Life Insurance
Finite-Lived Intangible Assets [Line Items]
VOBA, amortization expense, year one	1.6
VOBA, amortization expense, year two	1.5
VOBA, amortization expense, year three	1.5
VOBA, amortization expense, year four	1.4
VOBA, amortization expense, year five	$ 1.3

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for present value of future profits of insurance contract acquired in business combination expected to be recognized during fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for present value of future profits of insurance contract acquired in business combination expected to be recognized during fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for present value of future profits of insurance contract acquired in business combination expected to be recognized during next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for present value of future profits of insurance contract acquired in business combination expected to be recognized during third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for present value of future profits of insurance contract acquired in business combination expected to be recognized during second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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