Goodwill and Other Intangible Assets - Components of Other Intangible Assets (Detail) - USD ($) $ in Millions		Mar. 31, 2022	Dec. 31, 2021
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	$ 11.4	$ 11.4
Accumulated Amortization	[1]	(2.9)	(2.7)
Net Book Value	[1]	8.5	8.7
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		10.4	10.4
Accumulated Amortization		(2.3)	(2.1)
Net Book Value		8.1	8.3
Trade Names
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		1.0	1.0
Accumulated Amortization		(0.6)	(0.6)
Net Book Value		$ 0.4	$ 0.4

[1] The weighted-average remaining useful life of the unamortized intangible assets as of March 31, 2022 is approximately eleven years.