Postretirement Benefit Plans - Expenses Related to Defined Benefit and Retiree Health Care benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
U.S. defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6	$ 6	$ 17	$ 16
Interest cost	10	11	31	33
Expected return on plan assets	(12)	(10)	(36)	(31)
Recognized net actuarial loss	4	6	14	19
Amortization of prior service cost (credit)	0	0	0	0
Net periodic benefit costs	8	13	26	37
Settlement losses	7	11	19	14
Curtailment gain	0	0	0	0
Total, including other postretirement (gains) losses	15	24	45	51
U.S. retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	4	3
Interest cost	5	6	15	17
Expected return on plan assets	(5)	(5)	(16)	(15)
Recognized net actuarial loss	2	1	6	5
Amortization of prior service cost (credit)	0	1	3	3
Net periodic benefit costs	3	4	12	13
Settlement losses	0	0	0	0
Curtailment gain	0	0	0	0
Total, including other postretirement (gains) losses	3	4	12	13
Non-U.S. defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	9	26	29
Interest cost	13	17	40	52
Expected return on plan assets	(19)	(21)	(57)	(62)
Recognized net actuarial loss	6	6	18	19
Amortization of prior service cost (credit)	0	0	(1)	(1)
Net periodic benefit costs	9	11	26	37
Settlement losses	0	1	2	1
Curtailment gain	0	(2)	0	(2)
Total, including other postretirement (gains) losses	$ 9	$ 10	$ 28	$ 36