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Summary of Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Parenthetical) (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] |  |  |  |
Prepaid licensing and royalty, total impairment losses |  | $ 0 | $ 85 | $ 244
Property, plant and equipment, total impairment loss |  |  | 109 |
Intangible assets, total impairment losses |  |  | 15 |
Fair Value, Measurements, Nonrecurring |  |  |  |
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] |  |  |  |
Prepaid licensing and royalty, written down |  |  | 0 |
Prepaid licensing and royalty, total impairment losses |  |  | 85 |
Property, plant and equipment, total impairment loss | [1] |  | 109 |
Intangible assets, total impairment losses | [2] |  | $ 15 |
[1] | Impairment losses on certain property, plant, and equipment which were determined to be impaired: In 2019, we recognized an impairment loss of $109 thousand on property, plant and equipment as while the recent years’ operating losses were expected to continue in the short-term, the carrying amounts of those long-lived assets would not be recoverable based on cash flow projections.
[2] | Impairment losses on certain intangible assets which were determined to be impaired: In 2019, we recognized an impairment loss of $15 thousand on intangible assets as while the recent years’ operating losses were expected to continue in the short-term, the carrying amounts of those intangible assets would not be recoverable based on cash flow projections.

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- Definition The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275 + Details
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