Discontinued operations - schedule of transaction proceeds and net assets disposed (Details) - Discontinued Operations, Disposed of by Sale - Alliance Healthcare - USD ($) $ in Millions	Jun. 01, 2021	Jan. 06, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Estimated fair value of proceeds from disposition	$ 6,900
Estimated net assets disposed	5,800
Estimated gain before currency translation adjustments	1,100
Estimated amount of currency translation loss released due to disposition	(800)
Net gain on disposal of discontinued operation	322
Base consideration	$ 6,275	$ 6,275

Amount after tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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Amount of foreign currency translation gain (loss) in the disposal group, including discontinued operation, recognized in the statement of income as a result of the sale or complete or substantially complete liquidation of an investment in a foreign entity.

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