Employee Benefit Plans (Details 2) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Before tax basis amount in accumulated other comprehensive loss.
Total recognized at December 31	$ 5,286	$ 5,511
Other Benefits
Before tax basis amount in accumulated other comprehensive loss.
Net actuarial loss	207	(82)
Prior service (credit) costs	(287)	(315)
Total recognized at December 31	(80)	(397)
U.S. | Pension Benefits
Before tax basis amount in accumulated other comprehensive loss.
Net actuarial loss	4,258	4,653
Prior service (credit) costs	9	4
Total recognized at December 31	4,267	4,657
Int’l. | Pension Benefits
Before tax basis amount in accumulated other comprehensive loss.
Net actuarial loss	1,005	1,145
Prior service (credit) costs	94	106
Total recognized at December 31	$ 1,099	$ 1,251