Summary of Treasury Stock Activity (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) shares
Treasury Stock, Shares [Abstract]
Beginning Balance, Shares | shares	5,680,000
Restricted stock withholdings | shares	170,000	[1]
Restricted stock forfeitures | shares	30,000.00	[2]
Ending Balance, Shares | shares	5,880,000
Beginning Balance, Cost | $	$ 95.4
Restricted stock withholdings | $	2.1	[1]
Restricted stock forfeitures | $	0.0	[2]
Ending Balance, Cost | $	$ 97.5

[1] Holdings withheld shares as a result of the election by certain employees to satisfy their tax liabilities upon vesting in restricted stock and performance stock units. Holdings determined the number of shares to be withheld based upon market values of the common stock of Holdings on the vest dates, which ranged from $11.16 to $13.42 per share.

[2] Holdings repurchased forfeited restricted shares at a cost of $0.001 per share in accordance with its 2017 Omnibus Plan.