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Shareholders' equity Schedule of Dividends Declared (Details) | 12 Months Ended
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Dec. 31, 2020 SFr / shares | Dec. 31, 2020 $ / shares | Dec. 31, 2019 SFr / shares | Dec. 31, 2019 $ / shares | Dec. 31, 2018 SFr / shares | Dec. 31, 2018 $ / shares
Switzerland, Francs |  |  |  |  |  |
Dividends Declared [Line Items] |  |  |  |  |  |
Total dividend distributions per common share | SFr / shares | SFr 2.89 |  | SFr 2.94 |  | SFr 2.84 |
United States of America, Dollars |  |  |  |  |  |
Dividends Declared [Line Items] |  |  |  |  |  |
Total dividend distributions per common share | $ / shares |  | $ 3.09 |  | $ 2.98 |  | $ 2.90

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- Definition [Line Items] for Dividends Declared [Table] + References No definition available. + Details
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- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 + Details
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