Revenue Recognition (Performance Obligations) (Details) - USD ($) $ in Millions | Jun. 30, 2021 | Dec. 31, 2020 | Jun. 30, 2020 | Dec. 31, 2019 |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract with Customer, Liability | | $ 419 | $ 448 | $ 535 | $ 539 |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 333 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 43 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 22 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 21 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Subscription revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract with Customer, Liability | | $ 178 | 176 | | |
Subscription revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 106 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Subscription revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 37 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Subscription revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 18 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Subscription revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 17 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
VOI trial package revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract with Customer, Liability | | $ 101 | 115 | | |
VOI trial package revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 101 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
VOI trial package revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
VOI trial package revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
VOI trial package revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Exchange-related revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract with Customer, Liability | [1] | $ 63 | 59 | | |
Exchange-related revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 59 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Exchange-related revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 3 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Exchange-related revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 1 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Exchange-related revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
VOI incentive revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract with Customer, Liability | | $ 61 | 74 | | |
VOI incentive revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 61 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
VOI incentive revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
VOI incentive revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
VOI incentive revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Co-branded credit card programs revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract with Customer, Liability | | $ 13 | 16 | | |
Co-branded credit card programs revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 3 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Co-branded credit card programs revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 3 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Co-branded credit card programs revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 3 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Co-branded credit card programs revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 4 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Other revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract with Customer, Liability | | $ 3 | $ 8 | | |
Other revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 3 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Other revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Other revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Other revenue | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
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[1] | Includes contractual liabilities to accommodate members for cancellations initiated by the Company due to unexpected events. These amounts are included within Accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets. | |