Benefit Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign Plan [Member]
Components of Net Periodic Benefit Cost:
Service cost	$ 10	$ 9	$ 10
Interest cost	23	21	23
Expected return on plan assets	(21)	(19)	(20)
Amortization of prior service cost	0	(1)	0
Amortization of net loss	2	2	2
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	0
Total pension cost	14	12	15
UNITED STATES
Components of Net Periodic Benefit Cost:
Service cost	13	13	16
Interest cost	41	42	48
Expected return on plan assets	(69)	(68)	(70)
Amortization of prior service cost	6	7	7
Amortization of net loss	18	18	20
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	4	4	0
Total pension cost	$ 13	$ 16	$ 21