Retirement Benefit Plans - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure
Actual contribution to defined benefit pension plans	$ 15
Settlement loss	0	$ 26
US | Pension benefits
Defined Benefit Plan Disclosure
Defined benefit plan, benefit obligation, payment for settlement		50
Liquidation of plan assets		50
Decrease in benefit obligation		63
Settlement loss	0	26
US | Pension benefits | Former Employees
Defined Benefit Plan Disclosure
Defined benefit plan, benefit obligation, benefits paid		$ 13
Minimum
Defined Benefit Plan Disclosure
Defined benefit plan, expected future employer contributions, current fiscal year	15
Maximum
Defined Benefit Plan Disclosure
Defined benefit plan, expected future employer contributions, current fiscal year	$ 25