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Stock Option Plans - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands | 1 Months Ended | 3 Months Ended | 6 Months Ended
--- | --- | --- | ---
Mar. 31, 2016 | Feb. 28, 2014 | Jun. 30, 2020 | Jun. 30, 2019 | Mar. 31, 2019 | Jun. 30, 2020
Shares Available for Grant |  |  |  |  |  |
Beginning balance |  |  |  |  |  | 1,704,183
Exercised |  |  | $ 23 | $ 5 | $ 1 |
Ending balance |  |  | 2,822,995 |  |  | 2,822,995
Number of Options |  |  |  |  |  |
Beginning balance |  |  |  |  |  | 5,643,410
Ending balance |  |  | 5,561,098 |  |  | 5,561,098
2014 Plan |  |  |  |  |  |
Stock Option Plans |  |  |  |  |  |
Vesting period |  | 4 years |  |  |  |
Maximum exercise term |  | 10 years |  |  |  |
Exercise price of common stock of its fair value (as a percent) |  | 100.00% |  |  |  |
Maximum number of options that may be re-issued under the 2016 plan | 1,136,229 |  |  |  |  |
Shares Available for Grant |  |  |  |  |  |
Ending balance | 0 |  |  |  |  |
2016 Plan |  |  |  |  |  |
Stock Option Plans |  |  |  |  |  |
Vesting period | 4 years |  |  |  |  |
Maximum exercise term | 10 years |  |  |  |  |
Exercise price of common stock of its fair value (as a percent) | 100.00% |  |  |  |  |
Shares Available for Grant |  |  |  |  |  |
Beginning balance |  |  |  |  |  | 1,704,183
Additional shares authorized |  |  |  |  |  | 1,118,000
Granted |  |  |  |  |  | (190,000)
Forfeited |  |  |  |  |  | 190,812
Ending balance |  |  | 2,822,995 |  |  | 2,822,995
Number of Options |  |  |  |  |  |
Beginning balance |  |  |  |  |  | 5,643,410
Granted |  |  |  |  |  | 190,000
Exercised |  |  |  |  |  | (81,500)
Forfeited |  |  |  |  |  | (190,812)
Ending balance |  |  | 5,561,098 |  |  | 5,561,098
Weighted-Average Exercise Price |  |  |  |  |  |
Beginning balance (in dollars per share) |  |  |  |  |  | $ 8.05
Granted (in dollars per share) |  |  |  |  |  | 2.68
Exercised (in dollars per share) |  |  |  |  |  | 0.28
Forfeited (in dollars per share) |  |  |  |  |  | 7.07
Ending balance (in dollars per share) |  |  | $ 8.01 |  |  | $ 8.01

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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=116856206&loc=d3e5070-113901 + 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=116856206&loc=d3e5070-113901 + Details
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- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. + 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)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + 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=116856206&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + 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)(1)(i) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the 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 (a)(2) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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