Subsequent Event (Details) $ in Millions	1 Months Ended
Jul. 31, 2020 USD ($) item	Jun. 30, 2020
Subsequent Events
Optional lease extension term		10 years
Domestic Office Leases
Subsequent Events
Extended lease term	5 years
Number of lease renewal periods	1
Domestic Office Leases \| Subsequent Events
Subsequent Events
Number of properties leased	2
Extended lease term	5 years 5 months
Number of lease renewal periods	1
Optional lease extension term	5 years
Tenant improvement allowance and abatement \| $	$ 0.8

Represents the number of lease renewal periods allowed under the operating lease.

No definition available.

Name:	gkos_LesseeLeasingArrangementsOperatingLeasesNumberOfRenewalPeriods
Namespace Prefix:	gkos_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of tenant improvement allowance and abatement under the operating lease.

+ References

No definition available.

+ Details

Name:	gkos_LesseeLeasingArrangementsOperatingLeasesTenantImprovementAllowance
Namespace Prefix:	gkos_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the number of properties leased.

+ References

No definition available.

+ Details

Name:	gkos_NumberOfPropertiesLeased
Namespace Prefix:	gkos_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessor's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919359-209981

+ Details

Name:	us-gaap_LessorOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	srt_CounterpartyNameAxis=gkos_DomesticOfficeLeasesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: