XML 40 R29.htm IDEA: XBRL DOCUMENT
v3.21.2

STOCKHOLDERS' EQUITY - AT MARKET ISSUANCE SALES AGREEMENT (Details) - USD ($) |  | 3 Months Ended
--- | --- | ---
Sep. 04, 2020 | Sep. 30, 2021 | Jun. 30, 2021 | Mar. 31, 2021 | Jun. 30, 2020 | Mar. 31, 2020
At Market Issuance Sales Agreements [Line Items] |  |  |  |  |  |
Net cash proceeds from issuance of common stock after deducting sales commissions and other offering costs |  |  |  | $ 16,234,000 | $ 3,389,000 | $ 686,000
2020 Sales Agreement |  |  |  |  |  |
At Market Issuance Sales Agreements [Line Items] |  |  |  |  |  |
Aggregate offering price of common stock | $ 100,000,000 |  |  |  |  |
Maximum commission rate (as a percent) | 3.00% |  |  |  |  |
Issuance of common stock in connection with at market offering (in shares) |  | 0 | 0 | 7,948,505 |  |
Net cash proceeds from issuance of common stock after deducting sales commissions and other offering costs |  |  |  | $ 16,234,000 |  |
Common stock value available for future issuance |  | $ 83,000,000 |  |  |  |

X
- Definition At Market Issuance Sales Agreements. + References No definition available. + Details
Name: | gern_AtMarketIssuanceSalesAgreementsLineItems
Namespace Prefix: | gern_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the aggregate offering price for which the entity may elect to issue and sell shares of its common stock under the sales agreement. + References No definition available. + Details
Name: | gern_CommonStockAggregateOfferingPrice
Namespace Prefix: | gern_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Common stock value to be sold. + References No definition available. + Details
Name: | gern_CommonStockValueToBeSold
Namespace Prefix: | gern_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the percentage of maximum commission rate, based on gross proceeds of sale price per share of common stock sold through sales agent under the sales agreement. + References No definition available. + Details
Name: | gern_MaximumCommissionRate
Namespace Prefix: | gern_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of new stock issued during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_TypeOfArrangementAxis=gern_AtMarketIssuanceTwoThousandAndTwentySalesAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |