Benefit Plans (Net Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Defined Benefit Plans
CHANGE IN PROJECTED BENEFIT OBLIGATION:
Benefit obligation, beginning period	$ 1,172	$ 1,235
Service cost	13	16	$ 14
Interest cost	42	48	50
Employee contributions	0	0
Plan amendments	0	5
Defined Benefit Plan, Curtailments	2	0
Defined Benefit Plan, Settlements, Benefit Obligation	0	(3)
Benefits paid	(60)	(61)
Actuarial (gain) loss	19	(68)
Effect of foreign currency exchange rate changes	0	0
Benefit obligation, ending period	1,188	1,172	1,235
CHANGE IN PLAN ASSETS:
Fair value of plan assets, beginning period	1,021	1,061
Actual return on plan assets	61	(7)
Employer contributions	22	31
Employee contributions	0	0
Defined Benefit Plan, Settlements, Plan Assets	0	(3)
Benefits paid	(60)	(61)
Effect of foreign currency exchange rate changes	0	0
Fair value of plan assets, ending period	1,044	1,021	1,061
Funded status as of December 31	(144)	(151)
Foreign Defined Benefit Plans
CHANGE IN PROJECTED BENEFIT OBLIGATION:
Benefit obligation, beginning period	2,876	4,222
Service cost	13	15	16
Interest cost	344	340	473
Employee contributions	3	3
Plan amendments	(4)	2
Defined Benefit Plan, Curtailments	0	0
Defined Benefit Plan, Settlements, Benefit Obligation	0	0
Benefits paid	(303)	(292)
Actuarial (gain) loss	558	(158)
Effect of foreign currency exchange rate changes	505	(1,256)
Benefit obligation, ending period	3,992	2,876	4,222
CHANGE IN PLAN ASSETS:
Fair value of plan assets, beginning period	2,195	3,144
Actual return on plan assets	451	175
Employer contributions	138	86
Employee contributions	3	3
Defined Benefit Plan, Settlements, Plan Assets	0	0
Benefits paid	(303)	(292)
Effect of foreign currency exchange rate changes	340	(921)
Fair value of plan assets, ending period	2,824	2,195	$ 3,144
Funded status as of December 31	$ (1,168)	$ (681)