Postretirement Benefits (Details 2) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined contribution plans
Costs related to defined contribution plans	$ 118	$ 116	$ 311	$ 321
U.S. Plans
Defined contribution plans
Costs related to defined contribution plans	97	97	247	267
Non-U.S. Plans
Defined contribution plans
Costs related to defined contribution plans	$ 21	$ 19	$ 64	$ 54