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Financial Instruments - Summary of Interest Rate Swaps Held (Details) | Jun. 30, 2019 USD ($) interest_rate_swap | Mar. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
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Derivative [Line Items] |  |  |
Par Value of Debt |  | $ 5,000,000,000.0 |
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap | 19 |  |
Total Swap Notional Amount | $ 26,728,000,000 |  | $ 29,742,000,000
1.85% notes due 2020 | Interest rate swap contracts |  |  |
Derivative [Line Items] |  |  |
Stated interest rate (as percent) | 1.85% |  |
Par Value of Debt | $ 1,250,000,000 |  |
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap | 5 |  |
Total Swap Notional Amount | $ 1,250,000,000 |  |
3.875% notes due 2021 | Interest rate swap contracts |  |  |
Derivative [Line Items] |  |  |
Stated interest rate (as percent) | 3.875% |  |
Par Value of Debt | $ 1,150,000,000 |  |
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap | 5 |  |
Total Swap Notional Amount | $ 1,150,000,000 |  |
2.40% notes due 2022 | Interest rate swap contracts |  |  |
Derivative [Line Items] |  |  |
Stated interest rate (as percent) | 2.40% |  |
Par Value of Debt | $ 1,000,000,000 |  |
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap | 4 |  |
Total Swap Notional Amount | $ 1,000,000,000 |  |
2.35% notes due 2022 | Interest rate swap contracts |  |  |
Derivative [Line Items] |  |  |
Stated interest rate (as percent) | 2.35% |  |
Par Value of Debt | $ 1,250,000,000 |  |
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap | 5 |  |
Total Swap Notional Amount | $ 1,250,000,000 |  |

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