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Stockholders' Equity - Changes in Accumulated Other Comprehensive Loss, Net of Tax by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 375,515	$ 364,194	$ 372,944	$ 380,426
Other comprehensive income (loss) before reclassifications	(1,418)	2,963	(3,272)	3,162
Amounts reclassified from accumulated other comprehensive income (loss)	92	(295)	445	577
Net current period other comprehensive income (loss)	(1,326)	2,668	(2,827)	3,739
Ending Balance	363,753	369,593	363,753	369,593
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 Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(13,140)	(15,346)	(11,639)	(16,417)
Ending Balance	(14,466)	(12,678)	(14,466)	(12,678)
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(255)	206	32	(284)
Other comprehensive income (loss) before reclassifications	(29)	494	(358)	444
Amounts reclassified from accumulated other comprehensive income (loss)	(32)	(539)	10	1
Net current period other comprehensive income (loss)	(61)	(45)	(348)	445
Ending Balance	(316)	161	(316)	161
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(9,310)	(8,894)	(9,621)	(9,226)
Amounts reclassified from accumulated other comprehensive income (loss)	124	244	435	576
Net current period other comprehensive income (loss)	124	244	435	576
Ending Balance	(9,186)	(8,650)	(9,186)	(8,650)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(3,960)	(7,043)	(2,435)	(7,292)
Other comprehensive income (loss) before reclassifications	(1,389)	2,469	(2,914)	2,718
Net current period other comprehensive income (loss)	(1,389)	2,469	(2,914)	2,718
Ending Balance	$ (5,349)	$ (4,574)	$ (5,349)	$ (4,574)

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

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