Postretirement Benefits - Components of Net Periodic Pension Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 41,778	$ 33,826	$ 24,134
Pension plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	31,672	24,461	19,929
Interest cost	21,957	22,825	23,827
Expected return on assets	(32,331)	(29,561)	(27,862)
Prior service cost	631	632	8,211
Recognition of actuarial gain (loss)	19,849	15,469	29
Net periodic benefit cost	$ 41,778	$ 33,826	$ 24,134