Discontinued operations - narrative (Details) - Discontinued Operations, Disposed of by Sale - Alliance Healthcare - USD ($) $ in Millions	Jun. 01, 2021	Jan. 06, 2021	Aug. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration from disposal	$ 6,900	$ 6,500
Cash portion of consideration	6,275	$ 6,275
Shares issued as part of disposal (in shares)		2,000,000
Proceeds from disposal, subject to net working capital and net cash adjustments	6,700
Estimated gain before currency translation adjustments	1,100
Net gain on disposal	$ 322
Receivable for purchase consideration			$ 98

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

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