Supplemental Income Statement Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Supplemental Income Statement Information
Interest expense	$ 85	$ 57	$ 255	$ 156
Interest income	(15)	(13)	(52)	(33)
Pension and postretirement net periodic benefit cost (benefit)	(19)	(33)	(59)	(96)
Total	$ 51	$ 11	$ 144	$ 27