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Reconciliation of Beginning and Ending Balances of Assets Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs Level Three (Detail) - Marketable Securities - Debt and Equity Securities - Available-for-sale Securities $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Purchase	$ 10,000
Balance at end of year	10,000
Unrealized Gain (Loss) on Security
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total gains or (losses) (realized/unrealized), included in other comprehensive income	(351)
Foreign Currency Items
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total gains or (losses) (realized/unrealized), included in other comprehensive income	$ 351

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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 820
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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