Basis of Presentation and Significant Accounting Policies - Schedule of Accounting Standards Update (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2021
ASU 2018-12 Transition [Abstract]
Liability for future policy benefits	$ 6,968.0	$ 6,577.8
Deferred policy acquisition costs	433.1	248.0
Income before income taxes	(11.9)	174.9	$ 159.6
Minimum | Accounting Standards Update 2018-12
ASU 2018-12 Transition [Abstract]
Income before income taxes	15.0	20.0
Minimum | Accounting Standards Update 2018-12 | Measurement Input, Discount Rate
ASU 2018-12 Transition [Abstract]
Income before income taxes	7.0	15.0
Minimum | Accounting Standards Update 2018-12 | Deferred policy acquisition costs
ASU 2018-12 Transition [Abstract]
Income before income taxes	8.0	3.0
Minimum | Accounting Standards Update 2018-12 | Market risk benefits
ASU 2018-12 Transition [Abstract]
Income before income taxes	0.0	2.0
Maximum | Accounting Standards Update 2018-12
ASU 2018-12 Transition [Abstract]
Income before income taxes	31.0	35.0
Maximum | Accounting Standards Update 2018-12 | Measurement Input, Discount Rate
ASU 2018-12 Transition [Abstract]
Income before income taxes	17.0	25.0
Maximum | Accounting Standards Update 2018-12 | Deferred policy acquisition costs
ASU 2018-12 Transition [Abstract]
Income before income taxes	10.0	4.0
Maximum | Accounting Standards Update 2018-12 | Market risk benefits
ASU 2018-12 Transition [Abstract]
Income before income taxes	4.0	6.0
AOCI
ASU 2018-12 Transition [Abstract]
Liability for future policy benefits				$ (499.3)
Deferred policy acquisition costs				71.5
Market risk benefits				(1.3)
Total				(429.1)
Retained Earnings
ASU 2018-12 Transition [Abstract]
Liability for future policy benefits				(0.2)
Deferred policy acquisition costs				0.0
Market risk benefits				(5.4)
Total				$ (5.6)
AOCI and Retained Earnings | Minimum | Accounting Standards Update 2018-12
ASU 2018-12 Transition [Abstract]
Liability for future policy benefits	80.0	(375.0)
Deferred policy acquisition costs	(83.0)	58.0
Market risk benefits	(3.0)	(7.0)
Total	(6.0)	(324.0)
AOCI and Retained Earnings | Maximum | Accounting Standards Update 2018-12
ASU 2018-12 Transition [Abstract]
Liability for future policy benefits	100.0	(355.0)
Deferred policy acquisition costs	(79.0)	62.0
Market risk benefits	3.0	(1.0)
Total	$ 24.0	$ (294.0)