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Summary of Changes to Prepaid Licensing and Royalty Fees (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Prepaid Expenses [Line Items]
Balance at beginning of year	$ 44
Addition	(25)	$ (10)	$ (267)
Amortization and usage	(5)	(47)	(36)
Impairment charges (Note 4)	0	(85)	(244)
Balance at end of year	130	44
Prepaid Licensing and Royalty Fees
Prepaid Expenses [Line Items]
Balance at beginning of year	44	435	459
Addition	340	205	968
Amortization and usage	(254)	(511)	(747)
Exchange difference			(1)
Impairment charges (Note 4)		(85)	(244)
Balance at end of year	$ 130	$ 44	$ 435

X

- Definition

Impairment loss on prepaid licensing and royalty fees.

+ References

No definition available.

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- Definition

Prepaid expenses.

+ References

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- Definition

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
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-Publisher FASB
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-Topic 230
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

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- Definition

The amount of difference between the reported amount and the reporting currency-denominated amount. The default debit balance is based on the reported amount that is greater that the reporting currency-denominated amount.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6897108&loc=SL6897125-166521

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- Definition

The increase (decrease) during the reporting period in the amount of outstanding money paid in advance for goods or services that bring economic benefits for future periods.

+ References

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- Definition

Sum of the carrying amounts as of the balance sheet date of amounts paid in advance for expenses which will be charged against earnings in periods after one year or beyond the operating cycle, if longer.

+ References

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