Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Income (Loss) by Component, Net of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity attributable to parent at beginning of period	$ 655,947
Other comprehensive loss before reclassifications	(9,971)	$ 17,740
Amounts reclassified from accumulated other comprehensive loss	6,621	(6,517)
Net current-period other comprehensive income (loss)	(3,350)	11,223
Reclassification of stranded tax effects related to the Tax Act	(16,847)
Stockholders' equity attributable to parent at end of period	302,960	655,947
AOCI Attributable to Parent
Increase (Decrease) In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity attributable to parent at beginning of period	(78,410)	(89,633)
Stockholders' equity attributable to parent at end of period	(98,607)	(78,410)
Pension and Other Postretirement Benefits Items
Increase (Decrease) In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity attributable to parent at beginning of period	(73,629)	(84,852)
Other comprehensive loss before reclassifications	(9,971)	17,740
Amounts reclassified from accumulated other comprehensive loss	6,621	(6,517)
Net current-period other comprehensive income (loss)	(3,350)	11,223
Reclassification of stranded tax effects related to the Tax Act	(16,847)
Stockholders' equity attributable to parent at end of period	(93,826)	(73,629)
Foreign Currency Items
Increase (Decrease) In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity attributable to parent at beginning of period	(4,781)	(4,781)
Other comprehensive loss before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	0	0
Net current-period other comprehensive income (loss)	0	0
Reclassification of stranded tax effects related to the Tax Act	0
Stockholders' equity attributable to parent at end of period	$ (4,781)	$ (4,781)

Other Comprehensive Income Loss Other Adjustment Net Of Tax

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

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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