Benefit Plans - Pension Costs (Details) - Pension Plans - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 9
Interest cost	13	16
Expected return on plan assets	(19)	(22)
Net loss from experience differences	4	5
Prior service cost/(credit)	0	0
Settlement losses and other expenses	4	4
Net periodic benefit costs	3	12
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	30	31
Interest cost	37	51
Expected return on plan assets	(99)	(103)
Net loss from experience differences	29	38
Prior service cost/(credit)	(2)	(2)
Settlement losses and other expenses	2	0
Net periodic benefit costs	$ (3)	$ 15