Income taxes - Income before income taxes (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income before income taxes - U.S.	$ 5,672	$ 5,130	$ 3,953
Income before income taxes - Non-U.S.	1,014	950	977
Income before income taxes	$ 6,686	$ 6,080	$ 4,930

The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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-Subparagraph (SX 210.4-08.(h)(1)(i))
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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Publisher FASB
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
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The portion of earnings or loss from continuing operations before income taxes that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile.

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