Long-Term Debt (Detail) - USD ($) $ in Millions | Mar. 31, 2020 | Dec. 31, 2019 |
Debt Instrument [Line Items] | | |
Credit Facility | $ 2,500 | $ 0 |
Finance lease obligations | 156 | 157 |
Total debt | 12,233 | 10,940 |
Less: Current portion of long-term debt | (1,664) | (977) |
Long-term debt, noncurrent | 10,569 | 9,963 |
Series L Notes, interest rate of 3.3%, face amount of $350, maturing September 15, 2022 (effective interest rate of 3.4%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 349 | 349 |
Series M Notes, interest rate of 3.4%, face amount of $350, maturing October 15, 2020 (effective interest rate of 3.6%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 350 | 349 |
Series N Notes, interest rate of 3.1%, face amount of $400, maturing October 15, 2021 (effective interest rate of 3.4%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 399 | 398 |
Series O Notes, interest rate of 2.9%, face amount of $450, maturing March 1, 2021 (effective interest rate of 3.1%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 449 | 449 |
Series P Notes, interest rate of 3.8%, face amount of $350, maturing October 1, 2025 (effective interest rate of 4.0%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 346 | 346 |
Series Q Notes, interest rate of 2.3%, face amount of $750, maturing January 15, 2022 (effective interest rate of 2.5%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 747 | 747 |
Series R Notes, interest rate of 3.1%, face amount of $750, maturing June 15, 2026 (effective interest rate of 3.3%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 744 | 744 |
Series U Notes, interest rate of 3.1%, face amount of $291, maturing February 15, 2023 (effective interest rate of 3.1%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 291 | 291 |
Series V Notes, interest rate of 3.8%, face amount of $318, maturing March 15, 2025 (effective interest rate of 2.8%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 332 | 332 |
Series W Notes, interest rate of 4.5%, face amount of $278, maturing October 1, 2034 (effective interest rate of 4.1%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 291 | 291 |
Series X Notes, interest rate of 4.0%, face amount of $450, maturing April 15, 2028 (effective interest rate of 4.2%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 444 | 444 |
Series Y Notes, floating rate, face amount of $550, maturing December 1, 2020 (effective interest rate of 2.2% at March 31, 2020) | | |
Debt Instrument [Line Items] | | |
Senior notes | 549 | 549 |
Series Z Notes, interest rate of 4.2%, face amount of $350, maturing December 1, 2023 (effective interest rate of 4.4%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 348 | 347 |
Series AA Notes, interest rate of 4.7%, face amount of $300, maturing December 1, 2028 (effective interest rate of 4.8%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 297 | 297 |
Series BB Notes, floating rate, face amount of $300, maturing March 8, 2021 (effective interest rate of 1.6% at March 31, 2020) | | |
Debt Instrument [Line Items] | | |
Senior notes | 299 | 299 |
Series CC Notes, interest rate of 3.6%, face amount of $550, maturing April 15, 2024 (effective interest rate of 3.9%) | | |
Debt Instrument [Line Items] | | |
Senior notes | 591 | 564 |
Series DD Notes, interest rate of 2.1%, face amount of $550, maturing October 3, 2022 (effective interest rate of 2.4%) | | |
Debt Instrument [Line Items] | | |
Senior notes | $ 561 | 543 |
Senior Notes | Series L Notes, interest rate of 3.3%, face amount of $350, maturing September 15, 2022 (effective interest rate of 3.4%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 3.30% | |
Senior notes, face amount | $ 350 | |
Effective interest rate | 3.40% | |
Senior Notes | Series M Notes, interest rate of 3.4%, face amount of $350, maturing October 15, 2020 (effective interest rate of 3.6%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 3.40% | |
Senior notes, face amount | $ 350 | |
Effective interest rate | 3.60% | |
Senior Notes | Series N Notes, interest rate of 3.1%, face amount of $400, maturing October 15, 2021 (effective interest rate of 3.4%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 3.10% | |
Senior notes, face amount | $ 400 | |
Effective interest rate | 3.40% | |
Senior Notes | Series O Notes, interest rate of 2.9%, face amount of $450, maturing March 1, 2021 (effective interest rate of 3.1%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 2.90% | |
Senior notes, face amount | $ 450 | |
Effective interest rate | 3.10% | |
Senior Notes | Series P Notes, interest rate of 3.8%, face amount of $350, maturing October 1, 2025 (effective interest rate of 4.0%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 3.80% | |
Senior notes, face amount | $ 350 | |
Effective interest rate | 4.00% | |
Senior Notes | Series Q Notes, interest rate of 2.3%, face amount of $750, maturing January 15, 2022 (effective interest rate of 2.5%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 2.30% | |
Senior notes, face amount | $ 750 | |
Effective interest rate | 2.50% | |
Senior Notes | Series R Notes, interest rate of 3.1%, face amount of $750, maturing June 15, 2026 (effective interest rate of 3.3%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 3.10% | |
Senior notes, face amount | $ 750 | |
Effective interest rate | 3.30% | |
Senior Notes | Series U Notes, interest rate of 3.1%, face amount of $291, maturing February 15, 2023 (effective interest rate of 3.1%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 3.10% | |
Senior notes, face amount | $ 291 | |
Effective interest rate | 3.10% | |
Senior Notes | Series V Notes, interest rate of 3.8%, face amount of $318, maturing March 15, 2025 (effective interest rate of 2.8%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 3.80% | |
Senior notes, face amount | $ 318 | |
Effective interest rate | 2.80% | |
Senior Notes | Series W Notes, interest rate of 4.5%, face amount of $278, maturing October 1, 2034 (effective interest rate of 4.1%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 4.50% | |
Senior notes, face amount | $ 278 | |
Effective interest rate | 4.10% | |
Senior Notes | Series X Notes, interest rate of 4.0%, face amount of $450, maturing April 15, 2028 (effective interest rate of 4.2%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 4.00% | |
Senior notes, face amount | $ 450 | |
Effective interest rate | 4.20% | |
Senior Notes | Series Y Notes, floating rate, face amount of $550, maturing December 1, 2020 (effective interest rate of 2.2% at March 31, 2020) | | |
Debt Instrument [Line Items] | | |
Senior notes, face amount | $ 550 | |
Effective interest rate | 2.20% | |
Senior Notes | Series Z Notes, interest rate of 4.2%, face amount of $350, maturing December 1, 2023 (effective interest rate of 4.4%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 4.20% | |
Senior notes, face amount | $ 350 | |
Effective interest rate | 4.40% | |
Senior Notes | Series AA Notes, interest rate of 4.7%, face amount of $300, maturing December 1, 2028 (effective interest rate of 4.8%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 4.70% | |
Senior notes, face amount | $ 300 | |
Effective interest rate | 4.80% | |
Senior Notes | Series BB Notes, floating rate, face amount of $300, maturing March 8, 2021 (effective interest rate of 1.6% at March 31, 2020) | | |
Debt Instrument [Line Items] | | |
Senior notes, face amount | $ 300 | |
Effective interest rate | 1.60% | |
Senior Notes | Series CC Notes, interest rate of 3.6%, face amount of $550, maturing April 15, 2024 (effective interest rate of 3.9%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 3.60% | |
Senior notes, face amount | $ 550 | |
Effective interest rate | 3.90% | |
Senior Notes | Series DD Notes, interest rate of 2.1%, face amount of $550, maturing October 3, 2022 (effective interest rate of 2.4%) | | |
Debt Instrument [Line Items] | | |
Interest rate | 2.10% | |
Senior notes, face amount | $ 550 | |
Effective interest rate | 2.40% | |
Commercial paper | | |
Debt Instrument [Line Items] | | |
Commercial paper | $ 2,011 | 3,197 |
Other | | |
Debt Instrument [Line Items] | | |
Other | $ 179 | $ 247 |