Pension Plans and Other Postretirement Benefits - Net Periodic Defined Benefit Cost for Defined Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,000	$ 3,000	$ 8,000	$ 9,000
Interest cost on projected benefit obligation	28,000	29,000	86,000	87,000
Expected return on plan assets	(50,000)	(50,000)	(151,000)	(151,000)
Amortization of prior service credit	0	0	0	0
Amortization of net actuarial gain	0	(1,000)	(1,000)	(2,000)
Net periodic benefit	$ (19,000)	$ (19,000)	$ (58,000)	$ (57,000)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other costs of operations	Other costs of operations	Other costs of operations	Other costs of operations
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other costs of operations	Other costs of operations	Other costs of operations	Other costs of operations
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 1,000	$ 1,000
Interest cost on projected benefit obligation	1,000	1,000	2,000	2,000
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	(1,000)	0	(2,000)	(1,000)
Amortization of net actuarial gain	(1,000)	(1,000)	(2,000)	(2,000)
Net periodic benefit	$ (1,000)	$ 0	$ (1,000)	$ 0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other costs of operations	Other costs of operations	Other costs of operations	Other costs of operations
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other costs of operations	Other costs of operations	Other costs of operations	Other costs of operations