Retirement Plans - Change in Benefit Obligation, Fair Value of Plan Assets, and Funded Status of Pension Plans and Postretirement Medical Plan (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in fair value of plan assets
Beginning balance	$ 2,251
Ending balance	2,206	$ 2,251
Funded Pension Plans
Change in benefit obligation
Beginning balance	2,450	1,957
Service cost	51	45
Interest cost	93	91
Actuarial (gain) loss	(156)	470
Benefit payments	(85)	(77)
Plan curtailments	(4)	(3)
Special termination benefits	1	2
Foreign currency exchange rate changes	(29)	(35)
Ending balance	2,321	2,450	$ 1,957
Change in fair value of plan assets
Beginning balance	2,251	2,145
Actual return on plan assets	28	151
Employer contributions	44	68
Benefit payments	(85)	(77)
Foreign currency exchange rate changes	(32)	(36)
Ending balance	2,206	2,251	2,145
Funded status (plan assets greater (less) than benefit obligations) at December 31	(115)	(199)
Unrecognized net actuarial (gains) losses	775	859
Unfunded Pension Plan
Change in benefit obligation
Beginning balance	278	253
Service cost	16	12
Interest cost	9	9
Actuarial (gain) loss	(2)	61
Benefit payments	(42)	(57)
Plan curtailments	0	0
Special termination benefits	0	0
Foreign currency exchange rate changes	0	0
Ending balance	259	278	253
Change in fair value of plan assets
Beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	42	57
Benefit payments	(42)	(57)
Foreign currency exchange rate changes	0	0
Ending balance	0	0	0
Funded status (plan assets greater (less) than benefit obligations) at December 31	(259)	(278)
Unrecognized net actuarial (gains) losses	105	135
Postretirement Medical Plan
Change in benefit obligation
Beginning balance	94	97
Service cost	4	4	4
Interest cost	3	3	3
Actuarial (gain) loss	5	(4)
Benefit payments	(8)	(6)
Plan curtailments	0	0
Special termination benefits	0	0
Foreign currency exchange rate changes	0	0
Ending balance	98	94	97
Change in fair value of plan assets
Beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	8	6
Benefit payments	(8)	(6)
Foreign currency exchange rate changes	0	0
Ending balance	0	0	$ 0
Funded status (plan assets greater (less) than benefit obligations) at December 31	(98)	(94)
Unrecognized net actuarial (gains) losses	$ 0	$ (5)