Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Aug. 10, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax liabilities
Investments	$ (0.4)		$ (0.3)
Total deferred tax liabilities	(0.4)		(0.3)
Deferred tax assets
Deferred tax asset related to investments	102.3		39.0	$ 49.8
Net operating loss carryforwards	15.0		3.8
Total deferred tax assets	117.3	$ 89.0	42.8
Net deferred tax assets (liabilities)	$ 116.9		$ 42.5