Employee Benefit Plans (Details 1) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Consolidated Balance Sheet for pension and other postretirement benefit plans
Noncurrent employee benefit plans	$ (7,421)	$ (7,216)
Pension Benefits | United States
Consolidated Balance Sheet for pension and other postretirement benefit plans
Deferred charges and other assets	21	16
Accrued liabilities	(188)	(222)
Noncurrent employee benefit plans	(3,465)	(3,515)
Net amount recognized at December 31	(3,632)	(3,721)
Pension Benefits | Int’l.
Consolidated Balance Sheet for pension and other postretirement benefit plans
Deferred charges and other assets	448	199
Accrued liabilities	(100)	(75)
Noncurrent employee benefit plans	(1,122)	(1,119)
Net amount recognized at December 31	(774)	(995)
Other Benefits
Consolidated Balance Sheet for pension and other postretirement benefit plans
Deferred charges and other assets	0	0
Accrued liabilities	(174)	(163)
Noncurrent employee benefit plans	(2,614)	(2,386)
Net amount recognized at December 31	$ (2,788)	$ (2,549)