Benefit Plans - Qualified and Non-Qualified Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income or Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Net loss	$ 9,917	$ 3,843
Amortization of prior service cost	(35)	(35)
Amortization of actuarial loss	(625)	(381)
Total recognized in other comprehensive income	9,257	3,427
Total recognized in net periodic pension income and other comprehensive income/loss (before tax)	$ (453)	$ (5,607)

Amount recognized in net periodic benefit cost (credit) and other comprehensive (income) loss.

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Amount, before tax, after reclassification adjustment, of increase (decrease) in accumulated other comprehensive income from gain (loss) of defined benefit plan.

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Amount, before tax, of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) of defined benefit plan.

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Amount, before tax, of gain (loss) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Amount, before tax, of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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