Business and Significant Accounting Policies - Additional Information (Detail) $ in Millions		12 Months Ended
	Oct. 01, 2022 USD ($)	Dec. 31, 2022 USD ($) foundation trust segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Business And Significant Accounting Policies [Line Items]
Number of reportable segments | segment		2
Percentage of contractual participation		100.00%
Number of statutory trusts | trust		11
Number of charitable foundations | foundation		1
Estimated liability for return of premiums		$ 0.2	$ 4.7
Estimated amount of premiums receivables due		0.2	0.1
Impairment of goodwill and intangibles	$ 28.5	28.5	43.2	$ 0.0
Impairment of indefinite lived intangible assets	17.3	17.3
Impairment of goodwill	11.2	11.2
Goodwill		118.6	147.3
Amortization expense		0.0	0.0	1.1
Accumulated depreciation for property and equipment		144.7	158.8
Net book value of property and equipment		43.6	67.5
Depreciation expense		$ 22.3	$ 23.9	$ 24.1
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other assets	Other assets
Foreign currency translation adjustment gain (loss)		$ (4.2)	$ (35.3)
International Operations
Business And Significant Accounting Policies [Line Items]
Carrying value of reporting unit in excess of fair value			43.2
Goodwill		$ 0.0	28.7
Indefinite-lived intangible asset carrying value	$ 17.3		$ 60.5
Minimum
Business And Significant Accounting Policies [Line Items]
Useful life		3 years
Maximum
Business And Significant Accounting Policies [Line Items]
Useful life		39 years