Financing arrangements (Interest Rate and Cross-currency Swaps) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
1.25% notes due 2017 (1.25% 2017 Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note		1.25%
2.20% notes due 2019 (2.20% 2019 Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	2.20%
3.45% notes due 2020 (3.45% 2020 Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	3.45%
4.10% notes due 2021 (4.10% 2021 Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	4.10%
3.875% notes due 2021 (3.875% 2021 Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	3.875%
3.625% notes due 2022 (3.625% 2022 Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	3.625%
3.625% notes due 2024 (3.625% 2024 Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	3.625%
3.125% notes due 2025 (3.125% 2025 Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	3.125%		3.125%
2.60% notes due 2026 (2.60% 2026 notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	2.60%	2.60%
2.125% 2019 euro Notes [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	2.125%
1.25% notes due 2022 (1.25% 2022 euro Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	1.25%	1.25%
0.41% 2023 Swiss franc Bonds [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	0.41%	0.41%
2.00% 2026 euro Notes [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	2.00%	2.00%
5.50% 2026 pound sterling Notes [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	5.50%
4.00% 2029 pound sterling Notes [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	4.00%
Notes payable [Member]
Debt Instrument [Line Items]
Notional amount	$ 9,450	$ 6,650
Notes payable [Member] | 1.25% notes due 2017 (1.25% 2017 Notes) [Member]
Debt Instrument [Line Items]
Notional amount	0	850
Notes payable [Member] | 2.20% notes due 2019 (2.20% 2019 Notes) [Member]
Debt Instrument [Line Items]
Notional amount	1,400	1,400
Notes payable [Member] | 3.45% notes due 2020 (3.45% 2020 Notes) [Member]
Debt Instrument [Line Items]
Notional amount	900	900
Notes payable [Member] | 4.10% notes due 2021 (4.10% 2021 Notes) [Member]
Debt Instrument [Line Items]
Notional amount	1,000	1,000
Notes payable [Member] | 3.875% notes due 2021 (3.875% 2021 Notes) [Member]
Debt Instrument [Line Items]
Notional amount	1,750	1,750
Notes payable [Member] | 3.625% notes due 2022 (3.625% 2022 Notes) [Member]
Debt Instrument [Line Items]
Notional amount	750	750
Notes payable [Member] | 3.625% notes due 2024 (3.625% 2024 Notes) [Member]
Debt Instrument [Line Items]
Notional amount	1,400	0
Notes payable [Member] | 3.125% notes due 2025 (3.125% 2025 Notes) [Member]
Debt Instrument [Line Items]
Notional amount	1,000	0
Notes payable [Member] | 2.60% notes due 2026 (2.60% 2026 notes) [Member]
Debt Instrument [Line Items]
Notional amount	$ 1,250	$ 0
Notes payable [Member] | 2.125% 2019 euro Notes [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	2.125%
Notes payable [Member] | 1.25% notes due 2022 (1.25% 2022 euro Notes) [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	1.25%
Notes payable [Member] | 0.41% 2023 Swiss franc Bonds [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	0.41%
Notes payable [Member] | 2.00% 2026 euro Notes [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	2.00%
Notes payable [Member] | 4.00% 2029 pound sterling Notes [Member]
Debt Instrument [Line Items]
Stated contractual interest rate on note	4.00%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 1.25% notes due 2017 (1.25% 2017 Notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	0.40%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 2.20% notes due 2019 (2.20% 2019 Notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	0.60%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 3.45% notes due 2020 (3.45% 2020 Notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	1.10%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 4.10% notes due 2021 (4.10% 2021 Notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	1.70%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 3.875% notes due 2021 (3.875% 2021 Notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	2.00%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 3.625% notes due 2022 (3.625% 2022 Notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	1.60%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 3.625% notes due 2024 (3.625% 2024 Notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	1.40%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 3.125% notes due 2025 (3.125% 2025 Notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	0.90%
London Interbank Offered Rate (LIBOR) [Member] | Notes payable [Member] | 2.60% notes due 2026 (2.60% 2026 notes) [Member]
Debt Instrument [Line Items]
Derivative, effective interest rate	0.30%