Pensions and Other Post-retirement Benefits - Schedule of Reconciliation of Level Three Assets (Detail) - Significant Unobservable Inputs (Level 3) - Insurance contracts - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at January 1	$ 21,502	$ 17,033
Net realized and unrealized losses	2,564	5,602
Net purchases, issuances and settlements	330	(1,133)
Fair value of plan assets at December 31	$ 24,396	$ 21,502

Defined Benefit Plan, Net Realized And Unrealized Gains And Losses Included In Earnings

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

No definition available.

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- 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

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- Definition

Amount, measured using unobservable input, of increase (decrease) in plan asset of defined benefit plan from purchase, sale and settlement of trade associated with underlying investment.

+ References

+ Details

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