Retirement Plans - Reconciliation of Balances of Pension Benefit Obligation and Fair Value of Plan Assets (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in pension benefit obligation:
Benefit obligation at beginning of year	$ 290,600,000	$ 274,400,000
Service cost	500,000	800,000	$ 1,600,000
Interest cost	6,400,000	8,000,000.0	9,800,000
Net actuarial (gain) loss	(2,800,000)	22,600,000
Benefits paid	(15,300,000)	(15,200,000)
Benefit obligation at end of year	279,400,000	290,600,000	274,400,000
Change in plan assets:
Fair value of plan assets at beginning of year	262,800,000	243,700,000
Actual return on plan assets	34,800,000	34,300,000
Contributions by the company	0	0	0
Benefits paid	(15,300,000)	(15,200,000)
Fair value of plan assets at end of year	282,300,000	262,800,000	$ 243,700,000
Funded status of the plan (underfunded)	2,900,000	(27,800,000)
Amounts recognized in the consolidated balance sheet consist of:
Noncurrent assets (liabilities) - accrued benefit liability	2,900,000	(27,800,000)
Accumulated other comprehensive income	42,500,000	68,300,000
Net amount included in retained earnings	$ 45,400,000	$ 40,500,000