XML 65 R61.htm IDEA: XBRL DOCUMENT
v3.20.1

Commitments and Contingencies - Additional Information (Details) - USD ($) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Nov. 30, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Lessee Lease Description [Line Items] |  |  |  |
Non-cancelable operating sublease, expiration date for initial leased space |  | 2025-01 |  |
Non-cancelable operating sublease, expiration date for expansion space leased |  | 2022-12 |  |
Lessee, Operating Sublease, Existence of Option to Extend [true false] |  | true |  |
Lessee, operating sublease, option to extend |  | options to extend for the entire premises through October 2028 |  |
Operating sublease, annual increase percentage for base rent |  | 3.00% |  |
Monthly base rent for permanent space | $ 63,425 |  |  |
Monthly base rent for temporary space | $ 28,745 |  |  |
Option to extend lease term of permanent space | 12 months |  |  |
Annual increase percentage for lease charges | 3.00% |  |  |
Weighted average discount rate, operating leases |  | 7.00% |  |
Weighted average remaining lease term |  | 4 years |  |
Cash paid for operating lease liabilities |  | $ 3,000,000 |  |
Rent expense |  | $ 3,100,000 | $ 1,500,000 | $ 0
San Diego, California |  |  |  |
Lessee Lease Description [Line Items] |  |  |  |
Lease commencement date for permanent space | May 01, 2020 |  |  |
Lease expiration date for permanent space | Dec. 31, 2021 |  |  |
Lease commencement date for temporary space | Jan. 01, 2020 |  |  |

X
- Definition Annual increase percentage for lease charges. + References No definition available. + Details
Name: | goss_AnnualIncreasePercentageForLeaseCharges
Namespace Prefix: | goss_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lease commencement date for permanent space. + References No definition available. + Details
Name: | goss_LeaseCommencementDateForPermanentSpace
Namespace Prefix: | goss_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lease commencement date for temporary space. + References No definition available. + Details
Name: | goss_LeaseCommencementDateForTemporarySpace
Namespace Prefix: | goss_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Non-cancelable operating sublease, expiration date for expansion space leased. + References No definition available. + Details
Name: | goss_NonCancelableOperatingSubleaseExpirationDateForExpansionSpaceLeased
Namespace Prefix: | goss_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Non-cancelable operating sublease, expiration date for initial lease space. + References No definition available. + Details
Name: | goss_NonCancelableOperatingSubleaseExpirationDateForInitialLeaseSpace
Namespace Prefix: | goss_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Operating sublease, annual increase percentage for base rent. + References No definition available. + Details
Name: | goss_OperatingSubleaseAnnualIncreasePercentageForBaseRent
Namespace Prefix: | goss_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period for which lease of permanent space can be extended. + References No definition available. + Details
Name: | goss_PeriodForWhichLeaseOfPermanentSpaceCanBeExtended
Namespace Prefix: | goss_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Permanent monthly base rent. + References No definition available. + Details
Name: | goss_PermanentMonthlyBaseRent
Namespace Prefix: | goss_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Temporary monthly base rent. + References No definition available. + Details
Name: | goss_TemporaryMonthlyBaseRent
Namespace Prefix: | goss_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Date which lease or group of leases is set to expire, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_LeaseExpirationDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- 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_LesseeLeaseDescriptionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Indicates (true false) whether sublessee has option to extend operating sublease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -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_LesseeOperatingSubleaseExistenceOfOptionToExtend
Namespace Prefix: | us-gaap_
Data Type: | xbrli:booleanItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of terms and conditions of option to extend operating sublease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -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_LesseeOperatingSubleaseOptionToExtend
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(1) -URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980 + Details
Name: | us-gaap_OperatingLeasePayments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Weighted average discount rate for operating lease calculated at point in time. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(4) -URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971 + Details
Name: | us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(3) -URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980 + Details
Name: | us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717 + Details
Name: | us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_StatementGeographicalAxis=stpr_CA
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |