Retirement Benefit Plans - Funded status of plans with ABO in excess of plan assets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ (633)	$ (650)
Plan assets	425	450
Funded status of plan	(208)	(200)
United States
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan	(22)	(37)
Germany
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan	(107)	(95)
Other
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan	$ (79)	$ (68)