Pension and Other Postretirement Benefit Plans (Change in Benefit Obligation) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
United States Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year		$ 3,470	$ 3,796
Service cost		3	3	$ 2
Interest cost		147	150	167
Plan participants’ contributions		0	0
Actuarial loss (gain)		92	(164)
Benefits paid		(286)	(315)
Plan amendments		0	0
Settlements / curtailment (gain)		(11)	0
Foreign currency exchange rates		0	0
Benefit obligation, end of year		3,415	3,470	3,796
Accumulated benefit obligation, end of year		3,406	3,459
Foreign Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year		865	1,026
Service cost		5	5	5
Interest cost		27	31	22
Plan participants’ contributions		1	1
Actuarial loss (gain)		105	(11)
Benefits paid		(31)	(31)
Plan amendments		0	(3)
Settlements / curtailment (gain)		(16)	(66)
Foreign currency exchange rates		(101)	(87)
Benefit obligation, end of year		855	865	1,026
Accumulated benefit obligation, end of year		816	806
Other Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year		441	502
Service cost		7	2	3
Interest cost		18	19	24
Plan participants’ contributions		6	7
Actuarial loss (gain)		(16)	(32)
Benefits paid		(54)	(55)
Plan amendments	$ (138)	(30)	8
Settlements / curtailment (gain)		0	0
Foreign currency exchange rates		4	(10)
Benefit obligation, end of year		$ 376	$ 441	$ 502