Prior Period Consolidated Financial Statements - Consolidated Statement of Cash Flows (Unaudited) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows - operating activities
Net income	$ 6.6	$ 20.3
Adjustments to reconcile net income to net cash provided by operating activities:
Net investment losses	3.9	15.5
Depreciation and intangible asset amortization	6.6	3.8
Share-based compensation expense	2.0	2.1
Loss from equity method investments, net of dividends or distributions	10.0	1.6
Changes in:
Insurance liabilities	55.8	367.7
Amounts due under reinsurance agreements	0.3	(333.0)
Income tax liabilities	(9.9)	54.5
Other operating assets and liabilities	5.4	(40.1)
Other, net	5.7	3.3
Net cash provided by operating activities	86.4	95.7
Cash flows - investing activities
Net cash used in investing activities	(95.3)	(217.7)
Cash flows - financing activities
Net cash provided by (used in) financing activities	(6.5)	37.4
Net decrease in cash	(15.4)	(84.6)
Cash at beginning of period	42.8	133.7
Cash at end of period	27.4	49.1
Retained earnings
Cash flows - operating activities
Net income	6.6	20.3
Previously Reported
Cash flows - operating activities
Net income		14.5
Adjustments to reconcile net income to net cash provided by operating activities:
Net investment losses		15.5
Depreciation and intangible asset amortization		3.8
Share-based compensation expense		2.1
Loss from equity method investments, net of dividends or distributions		1.6
Changes in:
Insurance liabilities		450.5
Amounts due under reinsurance agreements		(357.7)
Income tax liabilities		3.4
Other operating assets and liabilities		(35.5)
Other, net		(2.5)
Net cash provided by operating activities		95.7
Cash flows - investing activities
Net cash used in investing activities		(217.7)
Cash flows - financing activities
Net cash provided by (used in) financing activities		37.4
Net decrease in cash		(84.6)
Cash at beginning of period	42.8	133.7
Cash at end of period		49.1
Previously Reported | Retained earnings
Cash flows - operating activities
Net income		14.5
Effect of the Adoption of ASU 2018-12
Cash flows - operating activities
Net income		5.8
Adjustments to reconcile net income 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 from equity method investments, net of dividends or distributions		0.0
Changes in:
Insurance liabilities		(82.8)
Amounts due under reinsurance agreements		24.7
Income tax liabilities		51.1
Other operating assets and liabilities		(4.6)
Other, net		5.8
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
Effect of the Adoption of ASU 2018-12 | Retained earnings
Cash flows - operating activities
Net income		$ 5.8