Earnings Per Share - Summary of Reconciliation of Numerator and Denominator Used to Calculate Basic and Diluted Loss Per Share of Common Stock (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 14, 2016
Numerator:
Net income	$ 143.7	$ 137.7	$ 141.0
Income allocated to participating securities	(0.9)	(1.7)	(2.6)
Net income for basic and diluted EPS	$ 142.8	$ 136.0	$ 138.4
Denominator:
Basic weighted average shares (in shares)	79.2	77.4	77.2
Effect of:
2 1/4% Notes (in shares)	2.4	4.5	4.4
Awards issued under equity plans (in shares)	0.1	0.0	0.1
Diluted weighted average shares (in shares)	81.7	81.9	81.7
Basic:
Basic earnings per share (in USD per share)	$ 1.80	$ 1.76	$ 1.79
Diluted:
Diluted earnings per share (in USD per share)	$ 1.75	$ 1.66	$ 1.69
2 1/4% Notes
Diluted:
Debt instrument interest rate stated percentage	2.25%	2.25%		2.25%
2 1/4% Notes | Convertible senior notes
Diluted:
Debt instrument interest rate stated percentage	2.25%