Long-term Employee Benefits - Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets (Details) - Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Change in plan assets:
Fair value of plan assets at beginning of year	$ 143.5	$ 134.1
Change in unrealized gain	(9.7)	12.5
Purchases, sales, issues and settlements	(3.4)	(3.8)
Transfers in/(out) of Level 3		0.7
Fair value of plan assets at end of year	130.4	143.5
Private market securities
Change in plan assets:
Fair value of plan assets at beginning of year	133.8	123.8
Change in unrealized gain	(10.1)	11.5
Purchases, sales, issues and settlements	(3.5)	(2.2)
Transfers in/(out) of Level 3		0.7
Fair value of plan assets at end of year	120.2	133.8
Debt and equity
Change in plan assets:
Fair value of plan assets at beginning of year	9.4	10.0
Change in unrealized gain	0.4	0.9
Purchases, sales, issues and settlements	0.1	(1.5)
Transfers in/(out) of Level 3		0.0
Fair value of plan assets at end of year	9.9	9.4
Real estate
Change in plan assets:
Fair value of plan assets at beginning of year	0.3	0.3
Change in unrealized gain	0.0	0.1
Purchases, sales, issues and settlements	0.0	(0.1)
Transfers in/(out) of Level 3		0.0
Fair value of plan assets at end of year	$ 0.3	$ 0.3