Percentage of employee contributions may be deferred to a defined contribution plan.

No definition available.

Name:	gemp_DefinedContributionPlanEmployeeContributionDeferredPercentage
Namespace Prefix:	gemp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee eligibility age criteria under defined contribution plan.

+ References

No definition available.

+ Details

Name:	gemp_DefinedContributionPlanEmployeeEligibilityAge
Namespace Prefix:	gemp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage employer matches of the employee's percentage contribution matched on one's contribution.

+ References

No definition available.

+ Details

Name:	gemp_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchOnOneSContribution
Namespace Prefix:	gemp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage employer matches of the employee's percentage contribution matched on overall contribution.

+ References

No definition available.

+ Details

Name:	gemp_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchOnOverallContribution
Namespace Prefix:	gemp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of employee contribution vested on contribution made by employee.

+ References

No definition available.

+ Details

Name:	gemp_EmployeeCompensationVestingPercentageOnContribution
Namespace Prefix:	gemp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Defined Contribution Plan (Details)	3 Months Ended		9 Months Ended
Defined Contribution Plan (Details)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) age	Sep. 30, 2018 USD ($)
Defined Contribution Plan Disclosure [Line Items]
Minimum age of employee to cover under the plan \| age			21
Employee compensation deferred percentage			100.00%
Employer match of employee contributions of eligible compensation			100.00%
Percentage of compensation matched by employer			3.00%
Employer match of over all employee contributions of eligible compensation			50.00%
Percentage of compensation matched by employer			3.00%
Percentage of employee contribution vested on their contribution			100.00%
Amount of discretionary matching contributions on employee deferrals \| $	$ 13,000	$ 30,000	$ 60,000	$ 84,000
Maximum
Defined Contribution Plan Disclosure [Line Items]
Percentage of compensation matched by employer			5.00%