Earnings Per Share And Shareholder's Equity - Earnings Per Share (Details) - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net income (loss)		$ (68.9)	$ (162.6)	$ 146.1
Denominator:
Weighted average share outstanding for basis EPS (in shares)		133.6	136.1	136.0
Dilutive effect of share-based awards (in shares)	[1]	0.0	1.1	0.5
Diluted (in shares)		133.6	137.2	136.5
Antidilutive share-based awards excluded from computation of diluted EPS (in shares)		0.0	0.0	1.5

[1] In the period of a loss from continuing operations, diluted shares equal basic shares