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Equity Incentive Plan (Tables) | 12 Months Ended
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Dec. 31, 2020
Share-based Payment Arrangement [Abstract] |
Summary of Stock Option and Restricted Stock Units Activity | The following is a summary of, the 2015 Plan, which includes restricted stock units:
|  | Unit (in Thousands) |
Available for grant at January 1, 2018 |  |  | 17,387 |
Restricted stock units granted |  |  | (1,622 | )
Restricted stock units forfeited |  |  | 22 |
Available for grant at December 31, 2018 |  |  | 15,787 |
Restricted stock units granted |  |  | (1,584 | )
Restricted stock units forfeited |  |  | 57 |
Available for grant at December 31, 2019 |  |  | 14,260 |
Restricted stock units granted |  |  | (1,692 | )
Restricted stock units forfeited |  |  | 57 |
Available for grant at December 31, 2020 |  |  | 12,625 |
Summary of Restricted Stock Units and Changes | Restricted Stock Units A summary of the status of restricted stock units and changes is as follows:
|  | Number of Non-vested Stock Units (in Thousands) |  |  | Weighted Average Grant Date Fair Value (US$) |  |  | Weight Average Remaining Recognition Period (Years) |
Non-vested at January 1, 2018 |  |  | 1,538 |  |  |  | 10.36 |  |  |  | 0.33 |
Restricted stock units granted |  |  | 1,622 |  |  |  | 13.86 |  |  |  |  |
Restricted stock units vested |  |  | (1,517 | ) |  |  | 9.79 |  |  |  |  |
Restricted stock units forfeited |  |  | (22 | ) |  |  | 11.75 |  |  |  |  |
Non-vested at December 31, 2018 |  |  | 1,621 |  |  |  | 13.85 |  |  |  | 0.38 |
Restricted stock units granted |  |  | 1,584 |  |  |  | 8.01 |  |  |  |  |
Restricted stock units vested |  |  | (1,505 | ) |  |  | 14.12 |  |  |  |  |
Restricted stock units forfeited |  |  | (57 | ) |  |  | 9.59 |  |  |  |  |
Non-vested at December 31, 2019 |  |  | 1,643 |  |  |  | 8.08 |  |  |  | 0.29 |
Restricted stock units granted |  |  | 1,692 |  |  |  | 9.40 |  |  |  |  |
Restricted stock units vested |  |  | (1,564 | ) |  |  | 8.02 |  |  |  |  |
Restricted stock units forfeited |  |  | (57 | ) |  |  | 9.31 |  |  |  |  |
Non-vested at December 31, 2020 |  |  | 1,714 |  |  |  | 9.37 |  |  |  | 0.31 |
Stock-based Compensation Expense | The following table shows total stock-based compensation expense included in the Consolidated Statements of Income for the years ended December 31, 2018, 2019 and 2020.
|  | Year Ended December 31 |
|  | 2018 |  |  | 2019 |  |  | 2020 |
|  | US$ |  |  | US$ |  |  | US$ |
Cost of sales |  |  | 390 |  |  |  | 305 |  |  |  | 253 |
Research and development |  |  | 13,278 |  |  |  | 9,927 |  |  |  | 10,132 |
Sales and marketing |  |  | 3,407 |  |  |  | 1,789 |  |  |  | 1,759 |
General and administrative |  |  | 3,704 |  |  |  | 2,570 |  |  |  | 2,445 |
|  |  | 20,779 |  |  |  | 14,591 |  |  |  | 14,589 |

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- Definition Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901 + Details
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