Revenue Recognition (Performance Obligations) (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract liabilities | | $ 448 | $ 539 | $ 519 | $ 556 |
Subscription revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract liabilities | | 176 | 206 | | |
VOI trial package revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract liabilities | | 115 | 145 | | |
VOI incentive revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract liabilities | | 74 | 107 | | |
Exchange-related revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract liabilities | [1] | 59 | 58 | | |
Co-branded credit card programs revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract liabilities | | 16 | 19 | | |
Other revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Contract liabilities | | $ 8 | $ 4 | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 361 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Subscription revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 105 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | VOI trial package revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 115 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | VOI incentive revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 74 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Exchange-related revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 55 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Co-branded credit card programs revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 4 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Other revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 8 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 43 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Subscription revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 37 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | VOI trial package revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | VOI incentive revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Exchange-related revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 3 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Co-branded credit card programs revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 3 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Other revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 21 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Subscription revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 17 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | VOI trial package revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | VOI incentive revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Exchange-related revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 1 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Co-branded credit card programs revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 3 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Other revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 23 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Subscription revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 17 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | VOI trial package revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | VOI incentive revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Exchange-related revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Co-branded credit card programs revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 6 | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Other revenue | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | | | | | |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period | | 1 year | | | |
Remaining performance obligations | | $ 0 | | | |
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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 Consolidated Balance Sheets. | |