Postretirement Benefits (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined contribution plans
Costs related to defined contribution plans	$ 95	$ 96
U.S. Plans
Defined contribution plans
Costs related to defined contribution plans	73	80
Non-U.S. Plans
Defined contribution plans
Costs related to defined contribution plans	$ 22	$ 16