Fair value measurement - (Fair Value of Financial Assets and Liabilities on Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Interest-bearing securities	$ 7,304	$ 9,845
Equity securities	831	477
Derivatives:
Total assets	8,400	10,671
Derivatives:
Contingent consideration obligations	342	33	$ 61	$ 72
Total liabilities	876	603
Foreign currency contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	183	28
Derivatives:
Foreign currency and cross-currency swap contracts	39	237
Cross-currency swap contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	66	255
Derivatives:
Foreign currency and cross-currency swap contracts	339	318
Interest rate swap contracts [Member]
Derivatives:
Interest rate swap contracts	16	66
Derivatives:
Interest rate swap contracts	156	15
U.S. Treasury notes [Member]
Assets:
Interest-bearing securities	47	130
U.S. Treasury bills [Member]
Assets:
Interest-bearing securities	1,400	4,948
Money market mutual funds [Member]
Assets:
Interest-bearing securities	5,856	4,765
Other short-term interest-bearing securities [Member]
Assets:
Interest-bearing securities	1	2
Quoted prices in active markets for identical assets (Level 1) [Member]
Assets:
Equity securities	611	477
Derivatives:
Total assets	7,914	10,320
Derivatives:
Contingent consideration obligations	0	0
Total liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) [Member] | Foreign currency contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	0	0
Derivatives:
Foreign currency and cross-currency swap contracts	0	0
Quoted prices in active markets for identical assets (Level 1) [Member] | Cross-currency swap contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	0	0
Derivatives:
Foreign currency and cross-currency swap contracts	0	0
Quoted prices in active markets for identical assets (Level 1) [Member] | Interest rate swap contracts [Member]
Derivatives:
Interest rate swap contracts	0	0
Derivatives:
Interest rate swap contracts	0	0
Quoted prices in active markets for identical assets (Level 1) [Member] | U.S. Treasury notes [Member]
Assets:
Interest-bearing securities	47	130
Quoted prices in active markets for identical assets (Level 1) [Member] | U.S. Treasury bills [Member]
Assets:
Interest-bearing securities	1,400	4,948
Quoted prices in active markets for identical assets (Level 1) [Member] | Money market mutual funds [Member]
Assets:
Interest-bearing securities	5,856	4,765
Quoted prices in active markets for identical assets (Level 1) [Member] | Other short-term interest-bearing securities [Member]
Assets:
Interest-bearing securities	0	0
Significant other observable inputs (Level 2) [Member]
Assets:
Equity securities	0	0
Derivatives:
Total assets	266	351
Derivatives:
Contingent consideration obligations	0	0
Total liabilities	534	570
Significant other observable inputs (Level 2) [Member] | Foreign currency contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	183	28
Derivatives:
Foreign currency and cross-currency swap contracts	39	237
Significant other observable inputs (Level 2) [Member] | Cross-currency swap contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	66	255
Derivatives:
Foreign currency and cross-currency swap contracts	339	318
Significant other observable inputs (Level 2) [Member] | Interest rate swap contracts [Member]
Derivatives:
Interest rate swap contracts	16	66
Derivatives:
Interest rate swap contracts	156	15
Significant other observable inputs (Level 2) [Member] | U.S. Treasury notes [Member]
Assets:
Interest-bearing securities	0	0
Significant other observable inputs (Level 2) [Member] | U.S. Treasury bills [Member]
Assets:
Interest-bearing securities	0	0
Significant other observable inputs (Level 2) [Member] | Money market mutual funds [Member]
Assets:
Interest-bearing securities	0	0
Significant other observable inputs (Level 2) [Member] | Other short-term interest-bearing securities [Member]
Assets:
Interest-bearing securities	1	2
Significant unobservable inputs (Level 3) [Member]
Assets:
Equity securities	220	0
Derivatives:
Total assets	220	0
Derivatives:
Contingent consideration obligations	342	33
Total liabilities	342	33
Significant unobservable inputs (Level 3) [Member] | Foreign currency contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	0	0
Derivatives:
Foreign currency and cross-currency swap contracts	0	0
Significant unobservable inputs (Level 3) [Member] | Cross-currency swap contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	0	0
Derivatives:
Foreign currency and cross-currency swap contracts	0	0
Significant unobservable inputs (Level 3) [Member] | Interest rate swap contracts [Member]
Derivatives:
Interest rate swap contracts	0	0
Derivatives:
Interest rate swap contracts	0	0
Significant unobservable inputs (Level 3) [Member] | U.S. Treasury notes [Member]
Assets:
Interest-bearing securities	0	0
Significant unobservable inputs (Level 3) [Member] | U.S. Treasury bills [Member]
Assets:
Interest-bearing securities	0	0
Significant unobservable inputs (Level 3) [Member] | Money market mutual funds [Member]
Assets:
Interest-bearing securities	0	0
Significant unobservable inputs (Level 3) [Member] | Other short-term interest-bearing securities [Member]
Assets:
Interest-bearing securities	$ 0	$ 0