Benefit Plans - Balances of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Prior service cost	$ 0	$ 0
Net actuarial loss	(37,560)	(33,799)
Total	(37,560)	(33,799)
Deferred taxes	(7,888)	(7,098)
Tax Effect of Extraordinary Item, Gain (Loss)	0	3,175
Accumulated other comprehensive loss	$ (29,672)	$ (23,526)

Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences from provisions, reserves, allowances, and accruals, classified as other.

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

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The tax effect of gains and losses from events or transactions meeting the criteria of unusual in nature and infrequent in occurrence, thereby meeting the criteria to be classified as an extraordinary item.

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