Retirement Plans - Reconciliation of Balances of Pension Benefit Obligation and Fair Value of Plan Assets (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in pension benefit obligation:
Benefit obligation at beginning of year	$ 211,900,000	$ 279,400,000
Service cost	3,300,000	500,000	$ 500,000
Interest cost	$ 10,700,000	$ 6,800,000	6,400,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Labor and Related Expense	Labor and Related Expense
Net actuarial loss (gain)	$ 8,800,000	$ (58,700,000)
Benefits paid	(18,700,000)	(16,100,000)
Benefit obligation at end of year	216,000,000.0	211,900,000	279,400,000
Change in plan assets:
Fair value of plan assets at beginning of year	212,500,000	282,300,000
Actual (loss) return on plan assets	35,100,000	(53,700,000)
Contributions by the company	0	0	0
Benefits paid	(18,700,000)	(16,100,000)
Fair value of plan assets at end of year	228,900,000	212,500,000	$ 282,300,000
Funded status of the plan (underfunded)	12,900,000	600,000
Amounts recognized in the consolidated balance sheet consist of:
Noncurrent assets - accrued benefit liability	12,900,000	600,000
Accumulated other comprehensive income	37,300,000	54,200,000
Net amount included in retained earnings	$ 50,200,000	$ 54,800,000