Postretirement benefits Schedule of amounts recognized in AOCI on a pretax basis (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member] | UNITED STATES
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	$ (227)	$ (207)
Prior Service Cost	0	0
Total	(227)	(207)
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	82	156
Prior Service Cost	6	(2)
Total	88	154
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	12	17
Prior Service Cost	(288)	(395)
Total	$ (276)	$ (378)