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Financial Instruments - Narrative (Details) | 9 Months Ended |  |
--- | --- | --- | ---
Sep. 30, 2018 USD ($) interest_rate_swap | May 31, 2018 USD ($) interest_rate_swap | Dec. 31, 2017 USD ($)
Derivative [Line Items] |  |  |
Number of interest rate swaps held (in interest rate swaps) | interest_rate_swap | 22 |  |
Notional amount | $ 26,549,000,000 |  | $ 25,595,000,000
Pretax net unrealized gain on derivatives maturing within next 12 months estimated to be reclassified from AOCI to sales | 75,000,000 |  |
Equity investments without readily determinable fair values | 749,000,000 |  |
Unrealized gains of equity investments | 199,000,000 |  |
Unrealized losses on investments | 25,000,000 |  |
Available-for-sale debt securities included in Short-term investments | 2,400,000,000 |  |
Available-for-sale debt securities maturing after one year through five years | 7,100,000,000 |  |
Cash and cash equivalents | 7,826,000,000 |  | 6,092,000,000
Fair value of loans payable and long-term debt, including current portion | 24,000,000,000 |  | 25,600,000,000
Carrying value of loans payable and long-term debt, including current portion | 23,600,000,000 |  | 24,400,000,000
Accounts receivable outstanding for more than one year | 40,000,000 |  |
Cash collateral received from counterparties | 54,000,000 |  | 3,000,000
Cash collateral advanced | 0 |  | 0
Afferent Pharmaceuticals |  |  |
Derivative [Line Items] |  |  |
Payment for contingent consideration | 175,000,000 |  |
Significant Other Observable Inputs (Level 2) |  |  |
Derivative [Line Items] |  |  |
Cash and cash equivalents | 7,800,000,000 |  |
Cash equivalents | 7,100,000,000 |  |
1.30% notes due 2018 | Interest rate swap contracts |  |  |
Derivative [Line Items] |  |  |
Number of interest rate swaps held (in interest rate swaps) | interest_rate_swap |  | 4 |
Notional amount |  | $ 250,000,000 |
Face amount of debt |  | $ 1,000,000,000.0 |
Stated interest rate (as percent) |  | 1.30% |
Derivatives Designated as Hedging Instruments |  |  |
Derivative [Line Items] |  |  |
Notional amount | $ 14,720,000,000 |  | 14,386,000,000
Derivatives Designated as Hedging Instruments | Maximum |  |  |
Derivative [Line Items] |  |  |
Maximum average period of maturities of contracts in years (less than) | 2 years |  |
Derivatives Not Designated as Hedging Instruments |  |  |
Derivative [Line Items] |  |  |
Notional amount | $ 11,829,000,000 |  | $ 11,209,000,000
Derivatives Not Designated as Hedging Instruments | Maximum |  |  |
Derivative [Line Items] |  |  |
Maximum average period of maturities of contracts in years (less than) | 1 year |  |

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