Retirement Plans - Changes in Accumulated Other Comprehensive Income Before Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Roll Forward]
Held for sale	$ 0	$ 2
Add back Held for sale	(2)	0
Effect of plan combinations	11	0
Amortization of actuarial loss	(1)	(1)	$ 0
Pension Plans, Defined Benefit
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Roll Forward]
Total retirement benefit recognized in accumulated other comprehensive income at beginning of year	13	10
Net actuarial loss (gain)	(8)	2
Translation difference	2	0
Total retirement benefit recognized in accumulated other comprehensive income at end of year	$ 15	$ 13	$ 10