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Stockholders' Equity - Changes in Accumulated Other Comprehensive Loss, Net of Tax by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 370,375	$ 363,715	$ 372,944	$ 380,426
Other comprehensive income (loss) before reclassifications	66	2,780	(1,854)	199
Amounts reclassified from accumulated other comprehensive income (loss)	389	(317)	353	872
Net current period other comprehensive income (loss)	455	2,463	(1,501)	1,071
Ending Balance	375,515	364,194	375,515	364,194
ASU 2018-02 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	385	385	385	385
Ending Balance	385	385	385	385
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(13,595)	(17,809)	(11,639)	(16,417)
Ending Balance	(13,140)	(15,346)	(13,140)	(15,346)
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(160)	(167)	32	(284)
Other comprehensive income (loss) before reclassifications	(272)	881	(329)	(50)
Amounts reclassified from accumulated other comprehensive income (loss)	177	(508)	42	540
Net current period other comprehensive income (loss)	(95)	373	(287)	490
Ending Balance	(255)	206	(255)	206
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(9,522)	(9,085)	(9,621)	(9,226)
Amounts reclassified from accumulated other comprehensive income (loss)	212	191	311	332
Net current period other comprehensive income (loss)	212	191	311	332
Ending Balance	(9,310)	(8,894)	(9,310)	(8,894)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(4,298)	(8,942)	(2,435)	(7,292)
Other comprehensive income (loss) before reclassifications	338	1,899	(1,525)	249
Net current period other comprehensive income (loss)	338	1,899	(1,525)	249
Ending Balance	$ (3,960)	$ (7,043)	$ (3,960)	$ (7,043)

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

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