Stockholders' Equity - Adjustments for Items Reclassified Out of AOCI (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	$ 1,132	$ 1,062
Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization relating to employee benefit plans	1,310	1,278
Less - related income taxes	178	216
Total reclassifications, net of tax	$ 1,132	$ 1,062

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