Name:	galt_ReturnOnInvestmentsPercentageAbstract
Namespace Prefix:	galt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Return on investments after eighth anniversary but before ninth anniversary of date of issuance.

No definition available.

Name:	galt_ReturnOnInvestmentsPercentagePeriodEight
Namespace Prefix:	galt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Return on investments after fifth anniversary but before sixth anniversary of date of issuance.

No definition available.

Name:	galt_ReturnOnInvestmentsPercentagePeriodFive
Namespace Prefix:	galt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Return on investments after fourth anniversary but before fifth anniversary of date of issuance.

No definition available.

Name:	galt_ReturnOnInvestmentsPercentagePeriodFour
Namespace Prefix:	galt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Return on investments percentage before second anniversary of date of issuance.

No definition available.

Name:	galt_ReturnOnInvestmentsPercentagePeriodOne
Namespace Prefix:	galt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Return on investments after seventh anniversary but before eighth anniversary of date of issuance.

No definition available.

Name:	galt_ReturnOnInvestmentsPercentagePeriodSeven
Namespace Prefix:	galt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Return on investments after sixth anniversary but before seventh anniversary of date of issuance.

No definition available.

Name:	galt_ReturnOnInvestmentsPercentagePeriodSix
Namespace Prefix:	galt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Return on investments after third anniversary but before fourth anniversary of date of issuance.

No definition available.

Name:	galt_ReturnOnInvestmentsPercentagePeriodThree
Namespace Prefix:	galt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Return on investments after second anniversary but before third anniversary of date of issuance.

No definition available.

Name:	galt_ReturnOnInvestmentsPercentagePeriodTwo
Namespace Prefix:	galt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

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

Aggregate amount of redemption requirements for each class or type of redeemable stock classified as temporary equity for each of the five years following the latest balance sheet date. The redemption requirement does not constitute an unconditional obligation that will be settled in a variable number of shares constituting a monetary value predominantly indexed to (a) a fixed monetary amount known at inception, (b) an amount inversely correlated with the residual value of the entity, or (c) an amount determined by reference to something other than the fair value of issuer's stock. Does not include mandatorily redeemable stock. The exception is if redemption is required upon liquidation or termination of the reporting entity.

No definition available.