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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4,423	$ 5,128	$ 13,237	$ 15,385
Interest cost on projected benefit obligation	22,060	15,468	60,407	46,404
Expected return on plan assets	(50,188)	(35,862)	(137,421)	(107,586)
Amortization of prior service cost (credit)	129	139	387	415
Amortization of net actuarial loss (gain)	4,974	22,254	14,921	66,763
Net periodic cost (benefit)	(18,602)	7,127	(48,469)	21,381
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	689	254	1,914	760
Interest cost on projected benefit obligation	581	328	1,607	984
Amortization of prior service cost (credit)	(693)	(1,185)	(2,079)	(3,554)
Amortization of net actuarial loss (gain)	(370)	(324)	(1,111)	(971)
Net periodic cost (benefit)	$ 207	$ (927)	$ 331	$ (2,781)