Summary of Treasury Stock Activity (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2022 USD ($) shares
Treasury Stock, Shares [Abstract]
Beginning Balance, Shares | shares	5,350,000
Restricted stock withholdings | shares	120,000	[1]
Restricted stock forfeitures | shares	50,000.00
Ending Balance, Shares | shares	5,520,000
Beginning Balance, Cost | $	$ 91.1
Restricted stock withholdings | $	2.1	[1]
Restricted stock forfeitures | $	0.0
Ending Balance, Cost | $	$ 93.2

[1] The Company withheld shares as a result of the election by certain employees to satisfy their tax liabilities upon vesting of restricted stock and restricted stock units. The Company determined the number of shares to be withheld based upon market values of the Company's common stock on the vest dates, which ranged from $15.18 to $17.51 per share.