Postretirement Benefit Plans - Benefit Obligations and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Funded status (FVPA – BO) at end of year	$ (133)	$ (113)
U.S. defined benefit plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	1,076	955
Service cost	22	21	$ 26
Interest cost	43	45	45
Participant contributions	0	0
Benefits paid	(8)	(66)
Medicare subsidy	0	0
Actuarial loss (gain)	(6)	133
Settlements	(94)	(12)
Curtailments	0	0
Plan amendments	0	0
Effects of exchange rate changes	0	0
Benefit obligation at end of year (BO)	1,033	1,076	955
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	1,082	941
Actual return on plan assets	(24)	132
Employer contributions (funding of qualified plans)	52	75
Employer contributions (payments for non-qualified plans)	11	12
Participant contributions	0	0
Benefits paid	(8)	(66)
Medicare subsidy	0	0
Settlements	(94)	(12)
Effects of exchange rate changes	0	0
Other	0	0
Fair value of plan assets at end of year (FVPA)	1,019	1,082	941
Funded status (FVPA – BO) at end of year	(14)	6
U.S. retiree health care plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	513	472
Service cost	5	4	5
Interest cost	20	22	20
Participant contributions	19	19
Benefits paid	(46)	(45)
Medicare subsidy	3	4
Actuarial loss (gain)	(21)	37
Settlements	0	0
Curtailments	0	0
Plan amendments	(30)	0
Effects of exchange rate changes	0	0
Benefit obligation at end of year (BO)	463	513	472
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	497	485
Actual return on plan assets	0	24
Employer contributions (funding of qualified plans)	1	10
Employer contributions (payments for non-qualified plans)	0	0
Participant contributions	19	19
Benefits paid	(46)	(45)
Medicare subsidy	0	4
Settlements	0	0
Effects of exchange rate changes	0	0
Other	(30)	0
Fair value of plan assets at end of year (FVPA)	441	497	485
Funded status (FVPA – BO) at end of year	(22)	(16)
Non-U.S. defined benefit plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	2,316	2,276
Service cost	35	39	41
Interest cost	53	68	61
Participant contributions	6	5
Benefits paid	(73)	(84)
Medicare subsidy	0	0
Actuarial loss (gain)	14	275
Settlements	(18)	(7)
Curtailments	0	(11)
Plan amendments	0	0
Effects of exchange rate changes	(102)	(245)
Benefit obligation at end of year (BO)	2,231	2,316	2,276
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	2,213	2,179
Actual return on plan assets	25	295
Employer contributions (funding of qualified plans)	72	64
Employer contributions (payments for non-qualified plans)	0	0
Participant contributions	6	5
Benefits paid	(73)	(84)
Medicare subsidy	0	0
Settlements	(18)	(7)
Effects of exchange rate changes	(91)	(239)
Other	0	0
Fair value of plan assets at end of year (FVPA)	2,134	2,213	$ 2,179
Funded status (FVPA – BO) at end of year	$ (97)	$ (103)