Long-term Compensation Plans - Schedule of Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Compensation expense	$ 6.0	$ 12.4	$ 19.3
Unrecognized compensation expense for awards expected to vest	$ 9.5
Weighted average remaining vesting period (months)	18 months
Equity classified RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Weighted average remaining vesting period (months)	20 months
Continuing Operations
Share-based Compensation Arrangement by Share-based Payment Award
Compensation expense	$ 6.0	11.8	15.4
Continuing Operations \| Equity classified RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Compensation expense	4.2	12.6	13.9
Continuing Operations \| Liability classified RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Compensation expense	0.9	(1.0)	0.7
Continuing Operations \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Compensation expense	0.9	0.2	0.8
Discontinued Operations
Share-based Compensation Arrangement by Share-based Payment Award
Compensation expense	$ 0.0	$ 0.6	$ 3.9

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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