Fair value measurement - Fair Value of Financial Assets and Liabilities on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets:
Available-for-sale securities:	$ 10,404	$ 4,335
Other investments	0	130
Equity securities	4,514	815
Derivatives:
Total assets	15,063	5,621
Derivatives:
Contingent consideration obligations	96	270	$ 342	$ 33
Total liabilities	1,188	1,668
Foreign currency forward contracts
Derivatives:
Derivative assets	145	287
Derivatives:
Derivative liabilities	116	76
Cross-currency swap contracts
Derivatives:
Derivative assets	0	54
Derivatives:
Derivative liabilities	405	541
Interest rate swap contracts
Derivatives:
Derivative assets	0
Derivatives:
Derivative liabilities	571	776
Forward interest rate contracts
Derivatives:
Derivative liabilities	0	5
U.S. Treasury bills
Assets:
Available-for-sale securities:	0	1,676
Money market mutual funds
Assets:
Available-for-sale securities:	10,266	2,659
Other short-term interest-bearing securities
Assets:
Available-for-sale securities:	138	0
Quoted prices in active markets for identical assets (Level 1)
Assets:
Other investments	0	0
Equity securities	4,514	480
Derivatives:
Total assets	14,780	4,815
Derivatives:
Contingent consideration obligations	0	0
Total liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) | Foreign currency forward contracts
Derivatives:
Derivative assets	0	0
Derivatives:
Derivative liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) | Cross-currency swap contracts
Derivatives:
Derivative assets	0	0
Derivatives:
Derivative liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) | Interest rate swap contracts
Derivatives:
Derivative assets	0
Derivatives:
Derivative liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) | Forward interest rate contracts
Derivatives:
Derivative liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) | U.S. Treasury bills
Assets:
Available-for-sale securities:	0	1,676
Quoted prices in active markets for identical assets (Level 1) | Money market mutual funds
Assets:
Available-for-sale securities:	10,266	2,659
Quoted prices in active markets for identical assets (Level 1) | Other short-term interest-bearing securities
Assets:
Available-for-sale securities:	0	0
Significant other observable inputs (Level 2)
Assets:
Other investments	0	130
Equity securities	0	0
Derivatives:
Total assets	283	471
Derivatives:
Contingent consideration obligations	0	0
Total liabilities	1,092	1,398
Significant other observable inputs (Level 2) | Foreign currency forward contracts
Derivatives:
Derivative assets	145	287
Derivatives:
Derivative liabilities	116	76
Significant other observable inputs (Level 2) | Cross-currency swap contracts
Derivatives:
Derivative assets	0	54
Derivatives:
Derivative liabilities	405	541
Significant other observable inputs (Level 2) | Interest rate swap contracts
Derivatives:
Derivative assets	0
Derivatives:
Derivative liabilities	571	776
Significant other observable inputs (Level 2) | Forward interest rate contracts
Derivatives:
Derivative liabilities	0	5
Significant other observable inputs (Level 2) | U.S. Treasury bills
Assets:
Available-for-sale securities:	0	0
Significant other observable inputs (Level 2) | Money market mutual funds
Assets:
Available-for-sale securities:	0	0
Significant other observable inputs (Level 2) | Other short-term interest-bearing securities
Assets:
Available-for-sale securities:	138	0
Significant unobservable inputs (Level 3)
Assets:
Other investments	0	0
Equity securities	0	335
Derivatives:
Total assets	0	335
Derivatives:
Contingent consideration obligations	96	270
Total liabilities	96	270
Significant unobservable inputs (Level 3) | Foreign currency forward contracts
Derivatives:
Derivative assets	0	0
Derivatives:
Derivative liabilities	0	0
Significant unobservable inputs (Level 3) | Cross-currency swap contracts
Derivatives:
Derivative assets	0	0
Derivatives:
Derivative liabilities	0	0
Significant unobservable inputs (Level 3) | Interest rate swap contracts
Derivatives:
Derivative assets	0
Derivatives:
Derivative liabilities	0	0
Significant unobservable inputs (Level 3) | Forward interest rate contracts
Derivatives:
Derivative liabilities	0	0
Significant unobservable inputs (Level 3) | U.S. Treasury bills
Assets:
Available-for-sale securities:	0	0
Significant unobservable inputs (Level 3) | Money market mutual funds
Assets:
Available-for-sale securities:	0	0
Significant unobservable inputs (Level 3) | Other short-term interest-bearing securities
Assets:
Available-for-sale securities:	$ 0	$ 0