Prior Period Consolidated Financial Statements - Consolidated Statement of Cash Flows (Details) - USD ($) $ in Millions		3 Months Ended										12 Months Ended
		Dec. 31, 2022		Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021		Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Cash flows - operating activities
Net income		$ (16.7)		$ 20.4	$ (4.2)	$ 20.3	$ 46.9		$ 20.2	$ 54.2	$ 49.1	$ 45.0		$ 19.8	[1],[2]	$ 170.4	[1],[2]
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net investment losses												24.0		56.5	[2]	11.0	[2]
Depreciation and intangible asset amortization												26.2		27.6	[2]	18.4	[2]
Share-based compensation expense												9.5		8.9	[2]	8.4	[2]
Loss (gain) from equity method investments, net of dividends or distributions												(14.5)		18.2	[2]	(41.5)	[2]
Other expense - goodwill and intangible asset impairments												0.0		4.8	[1],[2]	0.0	[1],[2]
Changes in:
Insurance liabilities												186.7		334.2	[2]	114.5	[2]
Amounts due under reinsurance agreements												(12.5)		(309.8)	[2]	7.4	[2]
Income tax liabilities												(15.0)		110.5	[2]	(91.2)	[2]
Other operating assets and liabilities												53.9		(109.4)	[2]	4.5	[2]
Other, net												(1.2)		10.2	[2]	3.0	[2]
Net cash provided by operating activities												302.1		171.5	[2]	204.9	[2]
Cash flows - investing activities
Net cash used in investing activities												(107.4)		(214.6)	[2]	(302.0)	[2]
Cash flows - financing activities
Net cash provided by (used in) financing activities												(207.8)		(47.8)	[2]	208.5	[2]
Net increase (decrease) in cash												(13.1)		(90.9)	[2]	111.4	[2]
Cash at beginning of year	[2]					133.7					22.3	42.8	[3]	133.7		22.3
Cash at end of year		42.8	[2],[3]				133.7	[2]				29.7		42.8	[2],[3]	133.7	[2]
Previously Reported
Cash flows - operating activities
Net income														(2.6)		142.8
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net investment losses														56.5		11.0
Depreciation and intangible asset amortization														27.6		18.4
Share-based compensation expense														8.9		8.4
Loss (gain) from equity method investments, net of dividends or distributions														18.2		(41.5)
Other expense - goodwill and intangible asset impairments														4.8		0.0
Changes in:
Insurance liabilities														440.5		46.9
Amounts due under reinsurance agreements														(348.2)		(1.5)
Income tax liabilities														(17.1)		8.5
Other operating assets and liabilities														(28.1)		8.9
Other, net														11.0		3.0
Net cash provided by operating activities														171.5		204.9
Cash flows - investing activities
Net cash used in investing activities														(214.6)		(302.0)
Cash flows - financing activities
Net cash provided by (used in) financing activities														(47.8)		208.5
Net increase (decrease) in cash														(90.9)		111.4
Cash at beginning of year						133.7					22.3	42.8		133.7		22.3
Cash at end of year		42.8					133.7							42.8		133.7
Effect of the Adoption of ASU 2018-12
Cash flows - operating activities
Net income														22.4		27.6
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net investment losses														0.0		0.0
Depreciation and intangible asset amortization														0.0		0.0
Share-based compensation expense														0.0		0.0
Loss (gain) from equity method investments, net of dividends or distributions														0.0		0.0
Other expense - goodwill and intangible asset impairments														0.0		0.0
Changes in:
Insurance liabilities														(106.3)		67.6
Amounts due under reinsurance agreements														38.4		8.9
Income tax liabilities														127.6		(99.7)
Other operating assets and liabilities														(81.3)		(4.4)
Other, net														(0.8)		0.0
Net cash provided by operating activities														0.0		0.0
Cash flows - investing activities
Net cash used in investing activities														0.0		0.0
Cash flows - financing activities
Net cash provided by (used in) financing activities														0.0		0.0
Net increase (decrease) in cash														0.0		0.0
Cash at beginning of year						$ 0.0					$ 0.0	$ 0.0		0.0		0.0
Cash at end of year		$ 0.0					$ 0.0							$ 0.0		$ 0.0

[1] Recast for the adoption of ASU 2018-12. See Note 1 of the Consolidated Financial Statements

[2] Recast for the adoption of ASU 2018-12. See Note 1 of the Consolidated Financial Statements

[3] Recast for the adoption of ASU 2018-12. See Note 1 of the Consolidated Financial Statements