Financing arrangements (Details Textual) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Feb. 29, 2020	Sep. 30, 2020	Sep. 30, 2019	May 31, 2020	Mar. 31, 2020
Debt Instrument [Line Items]
Repayments of Long-term Debt		$ 5,000	$ 4,514
Notes [Member]
Debt Instrument [Line Items]
Face amount	$ 5,000			$ 4,000
Notes [Member] | 4.563% notes due 2048 (4.563% 2048 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage		4.563%
Effective interest rate		6.30%
Notes [Member] | 4.663% notes due 2051 (4.663% 2051 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage		4.663%			4.663%
Effective interest rate		5.60%
Notes [Member] | Interest Expense [Member]
Debt Instrument [Line Items]
MakeWholePayments	$ 50
Notes [Member] | 1.90% notes due 2025 (1.90% 2025 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	1.90%	1.90%
Face amount	$ 500
Notes [Member] | 2.20% notes due 2027 (2.20% 2027 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	2.20%	2.20%		2.20%
Face amount	$ 750			$ 1,000
Notes [Member] | 2.45% notes due 2030 (2.45% 2030 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	2.45%	2.45%
Face amount	$ 1,250
Notes [Member] | 3.15% notes due 2040 (3.15% 2040 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	3.15%	3.15%		3.15%
Face amount	$ 1,250			$ 750
Notes [Member] | 3.375% notes due 2050 (3.375% 2050 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	3.375%	3.375%		3.375%
Face amount	$ 1,250			$ 1,000
Notes [Member] | 3.45% notes due 2020 (3.45% 2020 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	3.45%	3.45%
Notes [Member] | 4.10% notes due 2021 (4.10% 2021 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.10%	4.10%
Notes [Member] | 1.85% notes due 2021 (1.85% 2021 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	1.85%	1.85%
Notes [Member] | 3.875% notes due 2021 (3.875% 2021 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	3.875%	3.875%
Repayments of Long-term Debt	$ 300
Notes [Member] | 4.50% notes due 2020 (4.50% 2020 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%	4.50%
Notes [Member] | 2.30% notes due 2031 (2.30% 2031 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage		2.30%		2.30%
Face amount				$ 1,250
Notes [Member] | 2.125% notes due 2020 (2.125% 2020 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	2.125%	2.125%
Notes [Member] | 2.20% notes due 2020 (2.20% 2020 Notes) [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	2.20%	2.20%
Notes [Member] | Two Point Seven Seven Percent Notes Due Two Zero Five Three
Debt Instrument [Line Items]
Interest rate, stated percentage		2.77%
Effective interest rate		5.20%
Face amount		$ 940
Minimum [Member] | Debt Securities Payable [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Period without Payment of Make Whole Amount		1 month
Maximum [Member] | Debt Securities Payable [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Period without Payment of Make Whole Amount		6 months