Postretirement Benefit Plans - Schedule of Change in AOCI (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Defined benefit plan amounts recognized in other comprehensive income net actuarial loss portion roll forward
AOCI balance, net actuarial loss portion (net of taxes), beginning of period	$ 394
Adjustments, net actuarial loss	133
Recognized within net income, net actuarial loss	(65)
Tax effect, net actuarial loss	(20)
Cumulative effect of accounting changes, net actuarial loss	31	[1]
Total change to AOCI, net actuarial loss	79
AOCI balance, net actuarial loss portion (net of taxes), period end	473	[2]
Defined benefit plan amounts recognized in other comprehensive income prior service credit portion roll forward
AOCI balance, net prior service credit (net of taxes), beginning of period	(10)
Adjustments, prior service credit	7
Recognized within net income, prior service credit	4
Tax effect, prior service credit	(2)
Cumulative effect of accounting changes, prior service credit	(1)	[1]
Total change to AOCI, prior service credit	8
AOCI balance, net prior service credit (net of taxes), period end	(2)	[2]
United States | Defined benefit plan
Defined benefit plan amounts recognized in other comprehensive income net actuarial loss portion roll forward
AOCI balance, net actuarial loss portion (net of taxes), beginning of period	118
Adjustments, net actuarial loss	29
Recognized within net income, net actuarial loss	(39)
Tax effect, net actuarial loss	2
Cumulative effect of accounting changes, net actuarial loss	25	[1]
Total change to AOCI, net actuarial loss	17
AOCI balance, net actuarial loss portion (net of taxes), period end	135
United States | Retiree health care plan
Defined benefit plan amounts recognized in other comprehensive income net actuarial loss portion roll forward
AOCI balance, net actuarial loss portion (net of taxes), beginning of period	29
Adjustments, net actuarial loss	(16)
Recognized within net income, net actuarial loss	(2)
Tax effect, net actuarial loss	4
Cumulative effect of accounting changes, net actuarial loss	6	[1]
Total change to AOCI, net actuarial loss	(8)
AOCI balance, net actuarial loss portion (net of taxes), period end	21
Defined benefit plan amounts recognized in other comprehensive income prior service credit portion roll forward
AOCI balance, net prior service credit (net of taxes), beginning of period	(6)
Adjustments, prior service credit	0
Recognized within net income, prior service credit	3
Tax effect, prior service credit	(1)
Cumulative effect of accounting changes, prior service credit	(1)	[1]
Total change to AOCI, prior service credit	1
AOCI balance, net prior service credit (net of taxes), period end	(5)
Non-U.S. | Defined benefit plan
Defined benefit plan amounts recognized in other comprehensive income net actuarial loss portion roll forward
AOCI balance, net actuarial loss portion (net of taxes), beginning of period	247
Adjustments, net actuarial loss	120
Recognized within net income, net actuarial loss	(24)
Tax effect, net actuarial loss	(26)
Cumulative effect of accounting changes, net actuarial loss	0	[1]
Total change to AOCI, net actuarial loss	70
AOCI balance, net actuarial loss portion (net of taxes), period end	317
Defined benefit plan amounts recognized in other comprehensive income prior service credit portion roll forward
AOCI balance, net prior service credit (net of taxes), beginning of period	(4)
Adjustments, prior service credit	7
Recognized within net income, prior service credit	1
Tax effect, prior service credit	(1)
Cumulative effect of accounting changes, prior service credit	0	[1]
Total change to AOCI, prior service credit	7
AOCI balance, net prior service credit (net of taxes), period end	$ 3

[1] Reflects the adoption of ASU 2018-02. See Note 2 for additional information.

[2] Includes $30 million for the adoption of ASU 2018-02. See Note 2 for additional information.