Earnings (Loss) Per Share - Narrative (Details) - shares shares in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Earnings (Loss) Per Share
Earnout shares subject to forfeiture if achievement of stock prices are not met (in shares)	23.0
Employee Stock Option
Earnings (Loss) Per Share
Shares excluded from the calculation of diluted loss per share as their inclusion would have resulted in anti-dilutive effect on loss per share (in shares)	9.0	4.0
Dilutive effect of RSUs
Earnings (Loss) Per Share
Shares excluded from the calculation of diluted loss per share as their inclusion would have resulted in anti-dilutive effect on loss per share (in shares)	4.0
Performance Shares
Earnings (Loss) Per Share
Shares excluded from the calculation of diluted loss per share as their inclusion would have resulted in anti-dilutive effect on loss per share (in shares)	1.9

Number of shares subject to forfeiture if threshold stock price is not achieved.

No definition available.

Name:	gbtg_EarnOutSharesSharesSubjectToForfeitureIfThresholdStockPriceNotAchieved
Namespace Prefix:	gbtg_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482662/260-10-50-1

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
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

+ Details

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: