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Summary of Accounting Policies - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Accrual for chargebacks reflected as direct reduction to Accounts receivable | $ 198 | $ 196 |  |
Accrual for rebates included in Accrued and other current liabilities | 2,400 | 2,700 |  |
Depreciation expense | 1,500 | 1,600 | $ 1,600 |
Advertising expenses | 2,200 | 2,100 | $ 2,100 |
Accounting Standards Update 2016-01 | Forecast |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Increase in Retained earnings |  |  |  | $ 8
Accounting Standards Update 2016-16 | Forecast |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Increase in Retained earnings |  |  |  | 60
Accounting Standards Update 2017-07 |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Net periodic benefit cost (credit) | (510) | (530) |  |
Accounting Standards Update 2017-12 | Forecast |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Increase in Retained earnings |  |  |  | 11
Enterprise wide resource planning system |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Unamortized capitalized software costs | $ 449 | $ 452 |  |
Minimum |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of intangible assets | 2 years |  |  |
Minimum | Enterprise wide resource planning system |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of intangible assets | 6 years |  |  |
Minimum | Capitalized Software |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of intangible assets | 3 years |  |  |
Minimum | Building |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of property, plant and equipment | 25 years |  |  |
Minimum | Machinery and Equipment |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of property, plant and equipment | 3 years |  |  |
Maximum |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of intangible assets | 20 years |  |  |
Maximum | Enterprise wide resource planning system |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of intangible assets | 10 years |  |  |
Maximum | Capitalized Software |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of intangible assets | 5 years |  |  |
Maximum | Building |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of property, plant and equipment | 45 years |  |  |
Maximum | Machinery and Equipment |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Estimated useful life of property, plant and equipment | 15 years |  |  |
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Forecast |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Increase in Retained earnings |  |  |  | $ 5

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