Net Periodic Benefit Cost for Pension and Postretirement Benefit Plans (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
U.S. Pension Benefits
Net Periodic Cost:
Service cost	$ 353	$ 381	$ 706	$ 763
Interest cost	457	424	914	847
Expected return on assets	(629)	(622)	(1,258)	(1,244)
Amortization of:
Prior service cost	42	42	84	84
Net periodic benefit cost	223	225	446	450
U.S. Postretirement Medical Benefits
Net Periodic Cost:
Service cost	7	8	14	17
Interest cost	30	30	60	61
Expected return on assets	(1)	(4)	(2)	(8)
Amortization of:
Prior service cost	1	1	2	2
Net periodic benefit cost	37	35	74	72
International Pension Benefits
Net Periodic Cost:
Service cost	13	13	25	25
Interest cost	11	11	21	22
Expected return on assets	(15)	(16)	(29)	(31)
Amortization of:
Prior service cost	0	1	0	1
Net periodic benefit cost	$ 9	$ 9	$ 17	$ 17