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FORMER COLLABORATION AGREEMENT (Details)	Sep. 28, 2018	Sep. 27, 2018	Dec. 15, 2014 item	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Former Collaborative Arrangement [Line Items]
Amount due to Janssen Biotech, Inc.				$ 2,071,000	$ 2,610,000
Former Collaboration Agreement
Former Collaborative Arrangement [Line Items]
Number of agreed upon studies | item			2
Percentage of costs to be paid by Geron			50.00%
Percentage of costs to be paid by Janssen			50.00%
Percentage of costs to be paid by Geron before termination of Collaboration Agreement		50.00%
Percentage of costs to be paid by Geron after termination of Collaboration Agreement	100.00%
Amount due to Janssen Biotech, Inc.				$ 2,071,000
Former Collaborative Arrangement IP Exclusively Licensed
Former Collaborative Arrangement [Line Items]
Percentage of costs to be paid by Geron			50.00%
Percentage of costs to be paid by Janssen			50.00%

X

- Definition

Represents the percentage of costs that the company must pay after the termination of the Collaboration Agreement.

+ References

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- Definition

Represents the percentage of costs that the company must pay before the termination of the Collaboration Agreement

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- Definition

Represents the percentage of costs that Janssen must pay during certain phases of the agreement.

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Represents the percentage of costs that Geron must pay during certain phases of the agreement.

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Represents the number of agreed upon studies.

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Carrying amount as of the balance sheet date of obligations due to counterparty. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Former collaborative arrangement.

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