Postretirement Benefits - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Amounts included in accumulated other comprehensive loss
Net actuarial loss	$ 118,721	$ 142,678
Prior service cost	9,570	10,913
Net amount not yet recognized	$ 128,291	$ 153,591

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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- Definition

Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

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-Publisher FASB
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- Definition

Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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