Benefit Obligations (Schedule of Net Periodic Benefit Costs Recognized) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Recognized actuarial (gain) loss		$ 103		$ 127		$ 350
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		8		12		11
Interest cost		113		139		168
Expected return on plan assets		(177)		(209)		(214)
Amortization of prior service cost / (credit)		0		0		0
Recognized actuarial (gain) loss		101	[1]	134	[2]	339	[3]
Curtailment (gain) loss		0		(3)		0
Settlement (gain) loss		0		0		(78)
Special termination benefit		3		2		0
Total		48		75		226
Recognized actuarial (gain) loss relating to mortality table change	[2]	(48)		(62)		53
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		0		1		1
Interest cost		2		3		4
Expected return on plan assets		0		0		0
Amortization of prior service cost / (credit)		(3)		0		(83)
Recognized actuarial (gain) loss		2		(7)		11
Curtailment (gain) loss		0		0		0
Settlement (gain) loss		0		0		0
Special termination benefit		0		0		0
Total		$ 1		$ (3)		(67)
UNITED STATES | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement (gain) loss						(78)
UNITED STATES | Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost / (credit)						$ (84)

[1] Includes a gain of $48 million reflecting the incorporation of the RP-2016 mortality tables into the actuarial assumptions for the US pension plans.

[2] Includes a gain of $62 million reflecting the incorporation of the RP-2015 mortality tables into the actuarial assumptions for the US pension plans.

[3] Includes a loss of $53 million reflecting the incorporation of the RP-2014 mortality tables into the actuarial assumptions for the US pension plans.