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Retirement Plans - Defined Benefit Plan, Fair Value of Plan Assets, Unobservable Input Reconciliation (Detail) - Bank and Insurance Investment Contracts [Member] - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of defined benefit plan assets, beginning balance	$ 56,718	$ 51,963
Net purchases (sales) and appreciation (depreciation) of defined benefit plan assets	3,401	4,755
Fair value of defined benefit plan assets, ending balance	$ 60,119	$ 56,718

X

- Definition

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan.

+ References

No definition available.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

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X

- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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