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Segment Reporting - Reconciliation of Segment Profits to Income Before Taxes (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Segment Reporting Information [Line Items] |  |  |
Interest income | $ 59 | $ 274 | $ 343
Interest expense | (831) | (893) | (772)
Research and development | (13,558) | (9,872) | (9,752)
Restructuring costs | (578) | (638) | (632)
Income Before Taxes | 8,791 | 11,464 | 8,701
Total segment profits |  |  |
Segment Reporting Information [Line Items] |  |  |
Depreciation and amortization | (855) | (653) | (503)
Income Before Taxes | 31,373 | 29,926 | 26,633
Total segment profits | Pharmaceutical segment |  |  |
Segment Reporting Information [Line Items] |  |  |
Depreciation and amortization | (690) | (534) | (411)
Income Before Taxes | 29,722 | 28,324 | 24,871
Total segment profits | Animal Health |  |  |
Segment Reporting Information [Line Items] |  |  |
Depreciation and amortization | (164) | (109) | (82)
Income Before Taxes | 1,650 | 1,609 | 1,659
Total segment profits | Other segments |  |  |
Segment Reporting Information [Line Items] |  |  |
Depreciation and amortization | (1) | (10) | (10)
Income Before Taxes | 1 | (7) | 103
Other profits |  |  |
Segment Reporting Information [Line Items] |  |  |
Income Before Taxes | 140 | 363 | 6
Unallocated |  |  |
Segment Reporting Information [Line Items] |  |  |
Interest income | 59 | 274 | 343
Interest expense | (831) | (893) | (772)
Depreciation and amortization | (1,602) | (1,593) | (1,352)
Research and development | (13,072) | (9,499) | (9,432)
Amortization of purchase accounting adjustments | (1,168) | (1,406) | (2,664)
Restructuring costs | (578) | (638) | (632)
Charge related to the termination of a collaboration with Samsung | 0 | 0 | (423)
Other unallocated, net | $ (5,530) | $ (5,070) | $ (3,006)

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