Postemployment benefit plans (Details 7) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
U.S. Pension Benefits
Expected contributions and benefit payments for pension and other Postretirement benefit plans
Employer contribution expected for 2017	$ 350
Expected benefit payments for 2017	1,020
Expected benefit payments for 2018	980
Expected benefit payments for 2019	990
Expected benefit payments for 2020	990
Expected benefit payments for 2021	990
Expected benefit payments from 2022-2026	4,900
Total expected benefit payments	9,870
Non-U.S. Pension Benefits
Expected contributions and benefit payments for pension and other Postretirement benefit plans
Employer contribution expected for 2017	100
Expected benefit payments for 2017	190
Expected benefit payments for 2018	160
Expected benefit payments for 2019	160
Expected benefit payments for 2020	160
Expected benefit payments for 2021	170
Expected benefit payments from 2022-2026	970
Total expected benefit payments	1,810
Other Postretirement Benefits
Expected contributions and benefit payments for pension and other Postretirement benefit plans
Employer contribution expected for 2017	160
Expected benefit payments for 2017	310
Expected benefit payments for 2018	300
Expected benefit payments for 2019	300
Expected benefit payments for 2020	290
Expected benefit payments for 2021	280
Expected benefit payments from 2022-2026	1,320
Total expected benefit payments	2,800
Other postretirement benefits, Medicare Part D subsidy expected
Other postretirement benefits, Medicare Part D subsidy expected in 2016	15
Other postretirement benefits, Medicare Part D subsidy expected in 2017	15
Other postretirement benefits, Medicare Part D subsidy expected in 2018	20
Other postretirement benefits, Medicare Part D subsidy expected in 2019	20
Other postretirement benefits, Medicare Part D subsidy expected in 2020	20
Other postretirement benefits, Medicare Part D subsidy expected from 2021-2025	95
Total expected Medicare D subsidy receipts	$ 185