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Summary of Accounting Policies (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items] |  |  |
Product return period and expiration | 12 months |  |
Customer discounts | $ 13,100 | $ 11,800 | $ 10,700
Accrual for chargebacks reflected as direct reduction to accounts receivable | 249 | 233 |
Accrual for rebates included in accrued and other current liabilities | 2,900 | 2,200 |
Depreciation | 1,726 | 1,679 | 1,416
Advertising and promotion costs | 2,000 | 2,100 | 2,100
Decrease in deferred income taxes | (1,015) | (1,470) |
Accumulated other comprehensive loss | 6,634 | 6,193 |
Net periodic defined benefit plan (credit) cost other than service cost | $ (339) | $ (545) | $ (512)
Minimum |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Product return period | 3 months |  |
Estimated useful life of intangible assets | 2 years |  |
Minimum | Capitalized Software |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful life of intangible assets | 3 years |  |
Minimum | Buildings |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful life of property, plant and equipment | 25 years |  |
Minimum | Machinery, equipment and office furnishings |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful life of property, plant and equipment | 3 years |  |
Minimum | United States | Pharmaceutical segment |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Payment terms | 36 days |  |
Minimum | United States | Animal Health |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Payment terms | 30 days |  |
Minimum | Outside of the United States |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Payment terms | 30 days |  |
Maximum |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Product return period | 6 months |  |
Estimated useful life of intangible assets | 24 years |  |
Maximum | Capitalized Software |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful life of intangible assets | 10 years |  |
Maximum | Buildings |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful life of property, plant and equipment | 45 years |  |
Maximum | Machinery, equipment and office furnishings |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful life of property, plant and equipment | 15 years |  |
Maximum | United States |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Payment terms | 90 days |  |
Maximum | Outside of the United States |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Payment terms | 90 days |  |

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- Definition Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)(a)(4)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(23)(a)(3)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669686-108580 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 65 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 65 -Paragraph 2 -Subparagraph (g)(2)(ii) -URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e681-108580 + Details
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