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Debt (Narrative) (Details) |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 15, 2021 USD ($) | Apr. 01, 2021 USD ($) | Dec. 31, 2021 USD ($) Facility | Dec. 31, 2020 USD ($) | Mar. 31, 2020 USD ($) | Jan. 31, 2020 USD ($) | Mar. 31, 2020 USD ($) | Dec. 31, 2021 USD ($) Facility | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Apr. 09, 2021 USD ($) | Apr. 08, 2021 USD ($) | Apr. 02, 2021 USD ($) | May 31, 2020 USD ($) | Jan. 31, 2019 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Short-term debt |  |  | $ 17,000,000 | $ 517,000,000 |  |  |  | $ 17,000,000 | $ 517,000,000 |  |  |  |  |  |
Commercial paper outstanding |  |  | $ 0 |  |  |  |  | 0 |  |  |  |  |  |  |
Borrowings from term-loan and credit facilities |  |  |  |  |  |  |  | $ 0 | 1,000,000,000 | $ 300,000,000 |  |  |  |  |
Number of facilities terminated | Facility |  |  | 2 |  |  |  |  | 2 |  |  |  |  |  |  |
Repayments of principal in 2022 |  |  | $ 17,000,000 |  |  |  |  | $ 17,000,000 |  |  |  |  |  |  |
Repayments of principal in 2023 |  |  | 616,000,000 |  |  |  |  | 616,000,000 |  |  |  |  |  |  |
Repayments of principal in 2024 |  |  | 1,600,000,000 |  |  |  |  | 1,600,000,000 |  |  |  |  |  |  |
Repayments of principal in 2025 |  |  | 518,000,000 |  |  |  |  | 518,000,000 |  |  |  |  |  |  |
Repayments of principal in 2026 |  |  | 1,200,000,000 |  |  |  |  | 1,200,000,000 |  |  |  |  |  |  |
Other Debt Facilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving credit facility, amount outstanding |  |  | 0 | 0 |  |  |  | 0 | 0 |  |  |  |  |  |
Debt instrument, unused borrowing capacity |  |  | $ 508,000,000 | 573,000,000 |  |  |  | $ 508,000,000 | $ 573,000,000 |  |  |  |  |  |
Senior notes – 2.90% due 2051 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate |  |  | 2.90% |  |  |  |  | 2.90% |  |  |  |  |  |  |
2.75% Senior Debt Obligations Due January 2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repayments of debt |  |  | $ 500,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Interest rate |  |  | 2.75% |  |  |  |  | 2.75% |  |  |  |  |  |  |
Senior notes – 2.25% due 2030 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate |  |  | 2.25% |  |  |  |  | 2.25% |  |  |  |  |  |  |
Commercial Paper |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Short-term debt |  |  |  |  |  |  |  |  |  |  | $ 2,000,000,000 | $ 1,500,000,000 |  |  |
Revolving credit facility | Amended Revolving Credit Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving credit facility, borrowing capacity |  | $ 1,800,000,000 |  |  |  |  |  |  |  |  |  |  | $ 2,800,000,000 |  |
Revolving credit facility, amount outstanding |  |  | $ 0 |  |  |  |  | $ 0 |  |  |  |  |  |  |
Debt instrument, term |  | 5 years |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving credit facility | 364-day Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving credit facility, borrowing capacity |  | $ 1,000,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, term |  | 364 days |  |  |  |  |  |  |  |  |  |  |  |  |
Term loan facility | $500 Million One-Year Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving credit facility, borrowing capacity |  |  |  |  |  | $ 500,000,000 |  |  |  |  |  |  |  |  |
Debt instrument, term |  |  |  |  |  | 1 year |  |  |  |  |  |  |  |  |
Term loan facility | $500 Million Two-Year Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving credit facility, borrowing capacity |  |  |  |  |  | $ 500,000,000 |  |  |  |  |  |  |  |  |
Debt instrument, term |  |  |  |  |  | 2 years |  |  |  |  |  |  |  |  |
Term loan facility | $500 Million One-Year Term Loan and $500 Million Two-Year Term Loan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings from term-loan and credit facilities |  |  |  |  |  |  | $ 1,000,000,000 |  |  |  |  |  |  |  |
Senior Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 5,000,000,000
Repayments of debt | $ 500,000,000 |  |  | 700,000,000 | $ 500,000,000 |  |  |  |  |  |  |  |  |  |
Senior Notes | 2.31% Senior Debt Obligations Due 2031 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, amount |  |  | 400,000,000 |  |  |  |  | 400,000,000 |  |  |  |  |  |  |
Senior Notes | Senior notes – 2.90% due 2051 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, amount |  |  | $ 350,000,000 |  |  |  |  | $ 350,000,000 |  |  |  |  |  |  |
Senior Notes | Senior notes – 2.25% due 2030 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 750,000,000 |
Floating Rate Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repayments of debt |  |  |  | $ 300,000,000 |  |  |  |  |  |  |  |  |  |  |

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