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Common Stock - Stock Options - Additional Information (Detail) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Common shares reserved for options currently outstanding | 227,442 | 50,498 |
Weighted average fair value of stock options granted | $ 8.76 |  |
Unrecognized compensation expense related to stock options granted | $ 2,200,000 | $ 1,800,000 |
Estimated grant date fair value of stock options vested | 1,000,000 | 900,000 | $ 1,000,000
Aggregate intrinsic value of options exercised | 0 | $ 0 | $ 0
Aggregate intrinsic value of the outstanding options | 0 |  |
Aggregate intrinsic value of the exercisable outstanding options | $ 0 |  |
Stock Options [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Weighted-average period, restricted stock awards | 2 years 2 months 4 days | 2 years 2 months 4 days |
Restricted Stock Unit [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 4 years |  |
Common shares reserved for awards currently outstanding | 231 | 500 |
Weighted-average period, restricted stock awards | 6 months 29 days |  |
2018 Equity Incentive Plan [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Common shares reserved for issuance under incentive plan | 1,459 |  |
Award expiration period | 10 years |  |
2018 Equity Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 3 years |  |
2018 Equity Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 1 year |  |
2018 Equity Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 4 years |  |
2018 Equity Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 3 years |  |
2018 Equity Incentive Plan [Member] | Stock Options [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Common shares reserved for issuance under incentive plan | 215,514 |  |
Common shares reserved for options currently outstanding | 214,055 |  |
2017 Equity Incentive Plan [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award expiration period | 10 years |  |
2017 Equity Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 3 years |  |
2017 Equity Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 1 year |  |
2017 Equity Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 4 years |  |
2017 Equity Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 3 years |  |
2017 Equity Incentive Plan [Member] | Stock Options [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Common shares reserved for issuance under incentive plan | 13,156 |  |
2010 Performance Incentive Plan [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award expiration period | 10 years |  |
2010 Performance Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 3 years |  |
2010 Performance Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 1 year |  |
2010 Performance Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 4 years |  |
2010 Performance Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Award vesting period | 3 years |  |
2010 Performance Incentive Plan [Member] | Stock Options [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Common shares reserved for issuance under incentive plan | 462 |  |
Common shares reserved for options currently outstanding | 231 |  |
2010 Performance Incentive Plan [Member] | Restricted Stock Unit [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Common shares reserved for awards currently outstanding | 231 |  |

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- Definition Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + 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 (i) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition. + 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 (a)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + 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 (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + 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 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + 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 (d)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + 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 (d)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + 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 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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