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Stockholders' Equity - Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 364,194	$ 445,975	$ 380,426	$ 446,279
Other comprehensive income (loss) before reclassifications	2,963	(2,525)	3,162	(2,741)
Amounts reclassified from accumulated other comprehensive income (loss)	(295)	114	577	266
Amounts reclassified to retained earnings				385
Net current period other comprehensive income (loss)	2,668	(2,411)	3,739	(2,090)
Ending Balance	369,593	394,955	369,593	394,955
ASU 2018-02 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	385	385	385
Amounts reclassified to retained earnings				385
Net current period other comprehensive income (loss)				385
Ending Balance	385	385	385	385
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	206	(271)	(284)	(563)
Other comprehensive income (loss) before reclassifications	494	(39)	444	372
Amounts reclassified from accumulated other comprehensive income (loss)	(539)	24	1	(95)
Net current period other comprehensive income (loss)	(45)	(15)	445	277
Ending Balance	161	(286)	161	(286)
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(8,894)	(7,770)	(9,226)	(8,041)
Amounts reclassified from accumulated other comprehensive income (loss)	244	90	576	361
Net current period other comprehensive income (loss)	244	90	576	361
Ending Balance	(8,650)	(7,680)	(8,650)	(7,680)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(7,043)	(6,439)	(7,292)	(5,812)
Other comprehensive income (loss) before reclassifications	2,469	(2,486)	2,718	(3,113)
Net current period other comprehensive income (loss)	2,469	(2,486)	2,718	(3,113)
Ending Balance	(4,574)	(8,925)	(4,574)	(8,925)
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(15,346)	(14,095)	(16,417)	(14,416)
Ending Balance	$ (12,678)	$ (16,506)	$ (12,678)	$ (16,506)

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Other comprehensive income loss net of tax due to changes in accounting standard.

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

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

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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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