Prior Period Consolidated Financial Statements - Consolidated Statement of Cash Flows (Unaudited) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Cash flows - operating activities
Net income	$ 11.7	$ 20.4	$ 5.5	$ 36.5
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net investment losses			29.8	43.8
Depreciation and intangible asset amortization			19.5	20.7
Share-based compensation expense			7.1	6.7
Loss (gain) from equity method investments, net of dividends or distributions			9.0	2.1
Changes in:
Insurance liabilities			122.3	223.5
Amounts due under reinsurance agreements			26.9	(304.3)
Income tax liabilities			8.1	125.1
Other operating assets and liabilities			(28.1)	(42.6)
Other, net			(0.9)	4.3
Net cash provided by operating activities			199.2	115.8
Cash flows - investing activities
Net cash used in investing activities			(85.6)	(295.9)
Cash flows - financing activities
Net cash provided by (used in) financing activities			(121.9)	82.6
Net decrease in cash			(8.3)	(97.5)
Cash at beginning of period			42.8	133.7
Cash at end of period	$ 34.5	36.2	34.5	36.2
Previously Reported
Cash flows - operating activities
Net income		13.9		15.9
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net investment losses				43.8
Depreciation and intangible asset amortization				20.7
Share-based compensation expense				6.7
Loss (gain) from equity method investments, net of dividends or distributions				2.1
Changes in:
Insurance liabilities				403.3
Amounts due under reinsurance agreements				(344.3)
Income tax liabilities				(6.0)
Other operating assets and liabilities				(31.0)
Other, net				4.6
Net cash provided by operating activities				115.8
Cash flows - investing activities
Net cash used in investing activities				(295.9)
Cash flows - financing activities
Net cash provided by (used in) financing activities				82.6
Net decrease in cash				(97.5)
Cash at beginning of period			42.8	133.7
Cash at end of period		36.2		36.2
Effect of the Adoption of ASU 2018-12
Cash flows - operating activities
Net income		6.5		20.6
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net investment losses				0.0
Depreciation and intangible asset amortization				0.0
Share-based compensation expense				0.0
Loss (gain) from equity method investments, net of dividends or distributions				0.0
Changes in:
Insurance liabilities				(179.8)
Amounts due under reinsurance agreements				40.0
Income tax liabilities				131.1
Other operating assets and liabilities				(11.6)
Other, net				(0.3)
Net cash provided by operating activities				0.0
Cash flows - investing activities
Net cash used in investing activities				0.0
Cash flows - financing activities
Net cash provided by (used in) financing activities				0.0
Net decrease in cash				0.0
Cash at beginning of period			$ 0.0	0.0
Cash at end of period		$ 0.0		$ 0.0