Employee Benefit Plans - Summary of Components of Net Periodic Benefit Cost and Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other changes in plan assets and benefit obligations recognized in other comprehensive (loss) income:
Tax expense related to benefit plans included in other comprehensive income	$ 5,500	$ 2,100	$ 4,500
Defined benefit pension plans
Net periodic benefit cost (credit):
Service cost	4,479	4,223	4,045
Interest cost	19,309	18,117	17,961
Expected return on plan assets	(21,714)	(22,508)	(23,072)
Amortization of prior service cost (credit)	64	29	29
Recognized actuarial loss (gain)	7,585	8,518	8,362
Settlement loss	0	3,248	0
Curtailment loss	92	739	103
Net periodic benefit cost	9,815	12,366	7,428
Other changes in plan assets and benefit obligations recognized in other comprehensive (loss) income:
Net actuarial loss (gain)	28,740	(4,433)	46
Prior service cost (credit)	26	114	0
Amortization of prior service (cost) credit	(64)	(29)	(29)
Total recognized in other comprehensive (loss) income	28,702	(4,348)	17
Total recognized in net periodic benefit cost (credit) and other comprehensive (loss) income	38,517	8,018	7,445
Postretirement benefit plans
Net periodic benefit cost (credit):
Service cost	1	1	2
Interest cost	201	208	812
Expected return on plan assets	0	0	0
Amortization of prior service cost (credit)	(2,038)	(2,037)	0
Recognized actuarial loss (gain)	(384)	(320)	149
Settlement loss	0	0	0
Curtailment loss	0	0	0
Net periodic benefit cost	(2,220)	(2,148)	963
Other changes in plan assets and benefit obligations recognized in other comprehensive (loss) income:
Net actuarial loss (gain)	1,870	(276)	(2,746)
Prior service cost (credit)	0	0	(16,261)
Amortization of prior service (cost) credit	2,038	2,037	0
Total recognized in other comprehensive (loss) income	3,908	1,761	(19,007)
Total recognized in net periodic benefit cost (credit) and other comprehensive (loss) income	$ 1,688	$ (387)	$ (18,044)