Postretirement Benefits (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined contribution plans
Costs related to defined contribution plans	$ 98	$ 109	$ 193	$ 205
U.S. Plans
Defined contribution plans
Costs related to defined contribution plans	77	90	150	170
Non-U.S. Plans
Defined contribution plans
Costs related to defined contribution plans	$ 21	$ 19	$ 43	$ 35