Stockholders' Equity - Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax by Component (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 446,279	$ 497,911
Other comprehensive income (loss) before reclassifications	(929)	585
Amounts reclassified from accumulated other comprehensive income (loss)	75	127
Amounts reclassified to retained earnings	385	(3,220)
Net current period other comprehensive income (loss)	(469)	(2,508)
Ending Balance	443,547	475,736
ASU 2018-02 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified to retained earnings	385
Net current period other comprehensive income (loss)	385
Ending Balance	385
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(563)	2,567
Other comprehensive income (loss) before reclassifications	231	(257)
Amounts reclassified from accumulated other comprehensive income (loss)	(46)	65
Amounts reclassified to retained earnings		(3,220)
Net current period other comprehensive income (loss)	185	(3,412)
Ending Balance	(378)	(845)
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(8,041)	(4,286)
Amounts reclassified from accumulated other comprehensive income (loss)	121	62
Net current period other comprehensive income (loss)	121	62
Ending Balance	(7,920)	(4,224)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(5,812)	(1,576)
Other comprehensive income (loss) before reclassifications	(1,160)	842
Net current period other comprehensive income (loss)	(1,160)	842
Ending Balance	(6,972)	(734)
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(14,416)	(3,295)
Ending Balance	$ (14,885)	$ (5,803)