Fair value measurement (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Assets:
Interest-bearing securities	$ 7,159	$ 9,845
Equity securities	403	477
Derivatives:
Total assets	7,851	10,671
Derivatives:
Contingent consideration obligations	48	33
Total liabilities	562	603
Foreign currency contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	62	28
Derivatives:
Foreign currency and cross-currency swap contracts	119	237
Cross-currency swap contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	182	255
Derivatives:
Foreign currency and cross-currency swap contracts	305	318
Interest rate swap contracts [Member]
Derivatives:
Interest rate swap contracts	45	66
Derivatives:
Interest rate swap contracts	90	15
Quoted prices in active markets for identical assets (Level 1) [Member]
Assets:
Equity securities	403	477
Derivatives:
Total assets	7,562	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
Significant other observable inputs (Level 2) [Member]
Assets:
Equity securities	0	0
Derivatives:
Total assets	289	351
Derivatives:
Contingent consideration obligations	0	0
Total liabilities	514	570
Significant other observable inputs (Level 2) [Member] | Foreign currency contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	62	28
Derivatives:
Foreign currency and cross-currency swap contracts	119	237
Significant other observable inputs (Level 2) [Member] | Cross-currency swap contracts [Member]
Derivatives:
Foreign currency and cross-currency swap contracts	182	255
Derivatives:
Foreign currency and cross-currency swap contracts	305	318
Significant other observable inputs (Level 2) [Member] | Interest rate swap contracts [Member]
Derivatives:
Interest rate swap contracts	45	66
Derivatives:
Interest rate swap contracts	90	15
Significant unobservable inputs (Level 3) [Member]
Assets:
Equity securities	0	0
Derivatives:
Total assets	0	0
Derivatives:
Contingent consideration obligations	48	33
Total liabilities	48	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
U.S. Treasury notes [Member]
Assets:
Interest-bearing securities	52	130
U.S. Treasury notes [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Assets:
Interest-bearing securities	52	130
U.S. Treasury notes [Member] | Significant other observable inputs (Level 2) [Member]
Assets:
Interest-bearing securities	0	0
U.S. Treasury notes [Member] | Significant unobservable inputs (Level 3) [Member]
Assets:
Interest-bearing securities	0	0
U.S. Treasury bills [Member]
Assets:
Interest-bearing securities	1,400	4,948
U.S. Treasury bills [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Assets:
Interest-bearing securities	1,400	4,948
U.S. Treasury bills [Member] | Significant other observable inputs (Level 2) [Member]
Assets:
Interest-bearing securities	0	0
U.S. Treasury bills [Member] | Significant unobservable inputs (Level 3) [Member]
Assets:
Interest-bearing securities	0	0
Money market mutual funds [Member]
Assets:
Interest-bearing securities	5,707	4,765
Money market mutual funds [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Assets:
Interest-bearing securities	5,707	4,765
Money market mutual funds [Member] | Significant other observable inputs (Level 2) [Member]
Assets:
Interest-bearing securities	0	0
Money market mutual funds [Member] | Significant unobservable inputs (Level 3) [Member]
Assets:
Interest-bearing securities	0	0
Other short-term interest-bearing securities [Member]
Assets:
Interest-bearing securities	0	2
Other short-term interest-bearing securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Assets:
Interest-bearing securities	0	0
Other short-term interest-bearing securities [Member] | Significant other observable inputs (Level 2) [Member]
Assets:
Interest-bearing securities	0	2
Other short-term interest-bearing securities [Member] | Significant unobservable inputs (Level 3) [Member]
Assets:
Interest-bearing securities	$ 0	$ 0