Pension and Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Credit) and Other Amounts Recognized in OCI (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	$ 258	$ 259
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Interest cost		40	43	51
Expected return on plan assets		(51)	(71)	(82)
Service cost
Amortization of net actuarial (gain) loss		22	28	23
Settlement charge		256
Other
Net periodic benefit cost (credit)		267	0	(8)
Recognized in OCI:
Amount due to net actuarial (gains) losses		(107)	11	22
Reclassification adjustment for net actuarial gains (losses) in net periodic benefit cost		(278)	(28)	(23)
Other
Total recognized in OCI		(385)	(17)	(1)
Net recognized in benefit cost (credit) and OCI		(118)	(17)	(9)
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		8	7	7
Expected return on plan assets		(3)	(3)	(3)
Service cost		8	7	7
Amortization of net actuarial (gain) loss		6	6	7
Settlement charge		3
Termination benefit				1
Curtailment		(1)
Other			2
Net periodic benefit cost (credit)		21	19	19
Recognized in OCI:
Amount due to net actuarial (gains) losses		33	4	4
Reclassification adjustment for net actuarial gains (losses) in net periodic benefit cost		(9)	(6)	(7)
Curtailment				(1)
Other			(2)
Total recognized in OCI		24	(4)	(4)
Net recognized in benefit cost (credit) and OCI		45	15	15
Other Postretirement Benefits Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Interest cost		0
Net periodic benefit cost (credit)		0
Recognized in OCI:
Amount due to net actuarial (gains) losses		1
Total recognized in OCI		1
Net recognized in benefit cost (credit) and OCI		1
Other Postretirement Benefits Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		3	3	3
Service cost			1	1
Amortization of net actuarial (gain) loss		(1)
Net periodic benefit cost (credit)		2	4	4
Recognized in OCI:
Amount due to net actuarial (gains) losses		2	(7)	2
Reclassification adjustment for net actuarial gains (losses) in net periodic benefit cost		1
Total recognized in OCI		3	(7)	2
Net recognized in benefit cost (credit) and OCI		$ 5	$ (3)	$ 6