Goodwill and Intangible Assets - Schedule of Future Amortization Expense (Details) $ in Millions	Dec. 31, 2019 USD ($)
Finite-Lived Intangible Assets [Line Items]
Definite-life intangible assets, amortization expense, 2020	$ 34.0
Definite-life intangible assets, amortization expense, 2021	28.0
Definite-life intangible assets, amortization expense, 2022	26.2
Definite-life intangible assets, amortization expense, 2023	24.5
Definite-life intangible assets, amortization expense, 2024	21.8
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Definite-life intangible assets, amortization expense, 2020	0.9
Definite-life intangible assets, amortization expense, 2021	0.8
Definite-life intangible assets, amortization expense, 2022	0.6
Definite-life intangible assets, amortization expense, 2023	0.5
Definite-life intangible assets, amortization expense, 2024	0.4
Agent Relationships
Finite-Lived Intangible Assets [Line Items]
Definite-life intangible assets, amortization expense, 2020	5.0
Definite-life intangible assets, amortization expense, 2021	5.0
Definite-life intangible assets, amortization expense, 2022	5.0
Definite-life intangible assets, amortization expense, 2023	5.0
Definite-life intangible assets, amortization expense, 2024	5.0
Internal-Use Software
Finite-Lived Intangible Assets [Line Items]
Definite-life intangible assets, amortization expense, 2020	24.1
Definite-life intangible assets, amortization expense, 2021	19.1
Definite-life intangible assets, amortization expense, 2022	17.9
Definite-life intangible assets, amortization expense, 2023	16.5
Definite-life intangible assets, amortization expense, 2024	14.0
Life Insurance
Finite-Lived Intangible Assets [Line Items]
VOBA, amortization expense, 2020	4.0
VOBA, amortization expense, 2021	3.1
VOBA, amortization expense, 2022	2.7
VOBA, amortization expense, 2023	2.5
VOBA, amortization expense, 2024	$ 2.4