Stockholders' Equity - Adjustments for Items Reclassified Out of AOCI (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	$ 1,336	$ 1,895
Employee Benefit Plans [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization relating to employee benefit plans	1,717	2,233
Less - related income taxes	381	338
Total reclassifications, net of tax	$ 1,336	$ 1,895