Employee Benefit Plans (Defined Benefit Pension Plans not Recognized as Component of Combined Net Period Benefit Cost) (Detail) - Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ (64,343)	$ (57,964)
Deferred tax benefit	13,512	12,210
Amounts included in accumulated other comprehensive loss, net of tax	$ (50,831)	$ (45,934)