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Equity Incentive Plans - Stock Options Outstanding (Details) - $ / shares | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2020 | Dec. 31, 2019
Number of Stock Options |  |
Beginning Balance (shares) | 2,227,193 |
Exercised (shares) | (13,000) |
Ending Balance (shares) | 2,214,193 | 2,227,193
Exercisable (shares) | 2,189,114 |
Weighted Average Grant Date Fair Value |  |
Beginning Balance (usd per share) | $ 4.01 |
Exercised (usd per share) | 3.93 |
Ending Balance (usd per share) | 4.01 | $ 4.01
Exercisable (usd per share) | 4.00 |
Weighted Average Exercise Price |  |
Beginning Balance (usd per share) | 13.93 |
Exercised (usd per share) | 13.38 |
Ending Balance (usd per share) | 13.94 | $ 13.93
Exercisable (usd per share) | $ 13.91 |
Weighted Average Contractual Life (years) |  |
Outstanding | 4 years 5 months 15 days | 4 years 11 months 15 days
Exercisable | 4 years 5 months 12 days |

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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the 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)(iii) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable 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)(iii) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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