Equity-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Equity-Based Compensation
Payment for employee's tax obligations					$ 42	$ 22
Total employees’ tax obligation	$ 1	$ 41	$ 6	$ 19
Equity-based compensation expense after tax	15		16		46	45
Employee Stock Purchase Plan
Equity-Based Compensation
Equity-based compensation expense	19		$ 20		$ 58	$ 58
Employee Stock Purchase Plan \| Class A common stock
Equity-Based Compensation
Shares purchased (in shares)					1,087,753
RSU
Equity-Based Compensation
Compensation expense related to unvested RSUs to be recognized	$ 88				$ 88
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition (in years)					1 year 9 months 18 days
RSU \| Management Incentive Plan
Equity-Based Compensation
Number of shares withheld to cover the option costs and taxes (in shares)					3,217,523
Payment for employee's tax obligations					$ 3
RSU \| Equity Incentive Plan 2022
Equity-Based Compensation
Awards granted (in shares)					7,000,000
Share-based compensation arrangement by share-based payment award anniversaries ratio					33.33%
Annual vesting percentage					33.33%
Number of shares withheld to cover the option costs and taxes (in shares)					4,678,160
Total employees’ tax obligation					$ 39
RSU \| Equity Incentive Plan 2022 \| Class A common stock
Equity-Based Compensation
Awards granted (in shares)					6,506,266
Performance Shares
Equity-Based Compensation
Share-based payment award, award vesting goal, percentage					50.00%
Expected volatility rate					47.40%
Fair value assumptions, expected term					2 years 9 months 18 days
Expected dividend rate					0.00%
Risk-free interest rate					3.94%
Share-based payment award, fair value assumptions, exercise price (in dollars per share)	$ 11.14				$ 11.14
Performance Shares \| Minimum
Equity-Based Compensation
Payout factor based on target attainment, percentage					0.00%
Performance Shares \| Maximum
Equity-Based Compensation
Payout factor based on target attainment, percentage					150.00%
Performance Shares \| Equity Incentive Plan 2022
Equity-Based Compensation
Awards granted (in shares)					774,644
Share-based payment award, award requisite service period (in year)					3 years
Equity instruments other than options, performance period					3 years
Earned by grantee percentage					187.50%

Global Business Travel Group, Inc. 10-Q