Refers to the number of years shares will automatically increase.

No definition available.

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Data Type:	xbrli:durationItemType
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- Definition

Refers to the percentage of annual increase which is equal to the company's fully diluted share.

+ References

No definition available.

+ Details

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Namespace Prefix:	gemp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, 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)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ 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)(3)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=gemp_InducementPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TitleOfIndividualAxis=gemp_EmployeesDirectorsAndConsultantsMember
Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
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Share-Based Compensation - Stock Options (Details) - shares	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Jan. 01, 2019	Dec. 31, 2017	Sep. 30, 2016	Apr. 30, 2016	Apr. 30, 2015
Stock Options, Additional Disclosures
Percentage of company's fully diluted shares	20.00%
A&R 2015 Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)	1,030,583	415,077	501,001	0
Number of years common shares automatically increase	10 years	10 years
Percentage of company's fully diluted shares		20.00%
Inducement Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)	249,479				300,000
Employees, Directors And Consultants \| 2015 Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)							320,615
Employees, Directors And Consultants \| A&R 2015 Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)						2,400,000
Employees, Directors And Consultants \| Inducement Plan
Stock Options, Additional Disclosures
Vesting period		4 years