Name:	giga_LeaseAbatementSubjectToConditions
Namespace Prefix:	giga_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Period within which rent abatement can be exercised.

No definition available.

Name:	giga_LeaseAbatementSubjectToConditionsTerm
Namespace Prefix:	giga_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents annual increase per rentable square foot for operating lease.

No definition available.

Name:	giga_LesseeOperatingLeaseAnnualIncreasePerRentableSquareFoot
Namespace Prefix:	giga_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

Amount of tenant improvements provided to the lessee.

No definition available.

Name:	giga_OperatingLeaseTenantImprovementsProvidedByLandlord
Namespace Prefix:	giga_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of lessee's undiscounted obligation for lease payments for operating lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

Name:	us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

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