Pension and Postretirement Benefit Plans - Components of net periodic benefit cost and other information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
United States Qualified and Non-qualified Pension Benefits
Net periodic benefit cost (benefit)
Service cost	$ 73	$ 60	$ 219	$ 180
Interest cost	163	169	491	507
Expected return on plan assets	(267)	(261)	(801)	(783)
Amortization of prior service cost (benefit)	(6)	1	(18)	3
Amortization of net actuarial (gain) loss	101	60	305	182
Net periodic benefit cost (benefit)	64	29	196	89
Net periodic benefit cost (benefit) after settlements, curtailments, special termination benefits and other	64	29	196	89
International Qualified and Non-qualified Pension Benefits
Net periodic benefit cost (benefit)
Service cost	36	36	118	107
Interest cost	49	65	159	194
Expected return on plan assets	(74)	(79)	(236)	(238)
Amortization of transition (asset) obligation		(1)	(1)	(1)
Amortization of prior service cost (benefit)	(3)	(4)	(10)	(12)
Amortization of net actuarial (gain) loss	34	31	110	93
Net periodic benefit cost (benefit)	42	48	140	143
Defined Benefit Plan Recognized Net Gain Loss Due To Settlements And Curtailments 1			(17)
Net periodic benefit cost (benefit) after settlements, curtailments, special termination benefits and other	42	48	123	143
Postretirement Benefits
Net periodic benefit cost (benefit)
Service cost	19	16	62	49
Interest cost	25	24	75	72
Expected return on plan assets	(23)	(22)	(68)	(67)
Amortization of prior service cost (benefit)	(10)	(12)	(26)	(36)
Amortization of net actuarial (gain) loss	18	14	56	43
Net periodic benefit cost (benefit)	29	20	99	61
Net periodic benefit cost (benefit) after settlements, curtailments, special termination benefits and other	$ 29	$ 20	$ 99	$ 61