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Segmentation of key figures - Narrative (Details) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 USD ($) segment | Jun. 30, 2019 USD ($) | Jun. 30, 2020 USD ($) segment | Jun. 30, 2019 USD ($)
Operating Segments [Abstract] |  |  |  |
Number of reporting segments | segment | 2 |  | 2 |
Disclosure of operating segments [line items] |  |  |  |
Segment contribution | $ (6) | $ 378 | $ 368 | $ 764
Surgical |  |  |  |
Disclosure of operating segments [line items] |  |  |  |
Segment contribution | (28) | 235 | 180 | 463
Vision Care |  |  |  |
Disclosure of operating segments [line items] |  |  |  |
Segment contribution | $ 22 | 143 | $ 188 | 301
Reclassification of Fair Value Adjustments of Contingent Consideration Liability | Surgical |  |  |  |
Disclosure of operating segments [line items] |  |  |  |
Segment contribution |  | 18 |  | 23
Reclassification of Fair Value Adjustments of Contingent Consideration Liability | Vision Care |  |  |  |
Disclosure of operating segments [line items] |  |  |  |
Segment contribution |  | $ 8 |  | $ 19

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