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Stock Incentive Plans - Narrative (Details) - USD ($) shares in Millions, $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Stock Incentive Plans Narratives [Abstract] |  |  |
Unrecognized compensation expense | $ 213 |  |
Compensation expense | $ 351 | $ 456 | $ 316
Weighted-average period for total unrecognized compensation expense for nonvested equity awards | 1 year 3 months 18 days |  |
Fair value of stock incentive awards vested | $ 275 | $ 287 | $ 317
Performance Share Units (PSUs) |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Performance period | 3 years |  |
Stock options |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Expiration period | 10 years |  |
Dividend yield | 4.25% | 3.90% | 3.69%
Expected volatility rate | 26.20% | 28.00% | 28.00%
Risk-free interest rate | 1.44% | 2.62% | 2.73%
Expected option life | 5 years 11 months 19 days | 6 years | 5 years 11 months 23 days
Performance-based Employee Stock Options |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Service period | 55 months |  |
Service-based Employee Stock Options | Minimum |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Service period | 19 months |  |
Service-based Employee Stock Options | Maximum |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Service period | 3 years |  |
Restricted Stock Awards (RSAs) |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Service period | 3 years |  |
Restricted Stock Units (RSUs) |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Service period | 3 years |  |
Cruise Stock Incentive Awards |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Unrecognized compensation expense | $ 863 |  |
Cruise Stock Incentive Awards | Stock options |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Expiration period | 10 years |  |
Granted (in shares) | 0.0 |  |
Cruise Stock Incentive Awards | Stock options | Minimum |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Service period | 4 years |  |
Cruise Stock Incentive Awards | Stock options | Maximum |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Service period | 10 years |  |
Cruise Stock Incentive Awards | Stock options and RSUs |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Weighted-average period for total unrecognized compensation expense for nonvested equity awards | 7 years 1 month 6 days |  |
Total units outstanding (in shares) | 79.3 |  |
Cruise Stock Incentive Awards | Restricted Stock Units (RSUs) |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Unrecognized compensation expense | $ 0 | $ 0 | $ 0
Cruise Stock Incentive Awards | Restricted Stock Units (RSUs) | Maximum |  |  |
Stock Incentive Plans Narratives [Abstract] |  |  |
Service period | 4 years |  |

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