Employee Benefit Plans (Summary of Amounts Recognized in Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss) arising during the period	$ (178)	$ (138)	$ (451)
Curtailment gain	31	0	$ 0
U.S.
Defined Benefit Plan Disclosure [Line Items]
Unrecognized net actuarial loss (gain)	684	710
Unrecognized prior service cost (credit)	3	6
Net gain (loss) arising during the period	(54)	(124)
Curtailment gain	0	0
Amortization of (gain) loss and settlements included in income	80	155
Net change during the period	26	31
Prior service credit arising during the period	0	0
Amortization of prior service cost (credit) included in income	3	3
Net change during the period	3	3
Int’l.
Defined Benefit Plan Disclosure [Line Items]
Unrecognized net actuarial loss (gain)	227	143
Unrecognized prior service cost (credit)	(5)	(7)
Net gain (loss) arising during the period	(129)	7
Curtailment gain	31	0
Amortization of (gain) loss and settlements included in income	14	15
Net change during the period	(84)	22
Prior service credit arising during the period	0	0
Amortization of prior service cost (credit) included in income	(1)	(1)
Net change during the period	(1)	(1)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Unrecognized net actuarial loss (gain)	(5)	2
Unrecognized prior service cost (credit)	(9)	(10)
Net gain (loss) arising during the period	7	(14)
Curtailment gain	0	0
Amortization of (gain) loss and settlements included in income	0	(1)
Net change during the period	7	(15)
Prior service credit arising during the period	0	0
Amortization of prior service cost (credit) included in income	(1)	(2)
Net change during the period	$ (1)	$ (2)