Postretirement Benefit Plans - Expense Related to Defined Benefit and Retiree Health Care Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
U.S. defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 22	$ 21	$ 26
Interest cost	43	45	45
Expected return on plan assets	(48)	(42)	(48)
Amortization of prior service cost (credit)	0	0	1
Recognized net actuarial loss	19	26	21
Net periodic benefit costs	36	50	45
Settlement losses	25	5	41
Curtailment gain	0	0	0
Total, including other postretirement losses (gains)	61	55	86
U.S. retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	4	5
Interest cost	20	22	20
Expected return on plan assets	(22)	(20)	(24)
Amortization of prior service cost (credit)	2	4	4
Recognized net actuarial loss	8	7	11
Net periodic benefit costs	13	17	16
Settlement losses	0	0	0
Curtailment gain	0	0	0
Total, including other postretirement losses (gains)	13	17	16
Non-U.S. defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	35	39	41
Interest cost	53	68	61
Expected return on plan assets	(76)	(80)	(67)
Amortization of prior service cost (credit)	(2)	(2)	(3)
Recognized net actuarial loss	24	24	31
Net periodic benefit costs	34	49	63
Settlement losses	2	1	4
Curtailment gain	0	(2)	(7)
Total, including other postretirement losses (gains)	$ 36	$ 48	$ 60