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Nature of Business and Summary of Significant Accounting Policies (Other Comprehensive Income) - Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
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Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |  |  |  |  |  |  |  |
Defined benefit plan adjustments – actuarial losses |  |  |  |  |  |  |  |  | $ 2,139 | $ (1,294) |
Income (Loss) before (Provision) Benefit for Income Taxes |  |  |  |  |  |  |  |  | (33,371) | 44,687 | $ 46,895
Tax expense |  |  |  |  |  |  |  |  | 14,029 | (20,847) | (11,666)
Total reclassifications for the period, net of tax | $ (8,447) | $ 7,589 | $ (7,670) | $ (10,814) | $ (11,110) | $ 15,898 | $ 12,401 | $ 6,651 | (19,342) | 23,840 | 35,229
Cost of sales |  |  |  |  |  |  |  |  | (325,712) | (363,265) | (345,451)
Reclassification Out of Accumulated Other Comprehensive Income [Member] |  |  |  |  |  |  |  |  |  |  |
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |  |  |  |  |  |  |  |
Defined benefit plan adjustments – actuarial losses |  |  |  |  |  |  |  |  | (196) | (406) | (156)
Income (Loss) before (Provision) Benefit for Income Taxes |  |  |  |  |  |  |  |  | 608 | 3,381 | 4,833
Tax expense |  |  |  |  |  |  |  |  | (148) | (1,423) | (1,897)
Total reclassifications for the period, net of tax |  |  |  |  |  |  |  |  | 460 | 1,958 | 2,936
Unrealized Gains (Losses) on Available-for-Sale Securities [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member] |  |  |  |  |  |  |  |  |  |  |
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net investment gain (loss) |  |  |  |  |  |  |  |  | $ 804 | 4,864 | 5,408
Impairment Expense [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member] |  |  |  |  |  |  |  |  |  |  |
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net investment gain (loss) |  |  |  |  |  |  |  |  |  | (180) | $ (419)
Net Losses on Derivatives Designated as Hedging Instruments [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member] |  |  |  |  |  |  |  |  |  |  |
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |  |  |  |  |  |  |  |
Cost of sales |  |  |  |  |  |  |  |  |  | $ (897) |

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- Definition The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(a),(d)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
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