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STOCKHOLDERS' EQUITY - Treasury Stock and Stock-based compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Feb. 27, 2020
Treasury Stock
Share repurchase program	200,000,000.0
Stock repurchase program period	3 years
Stock Based Compensation Expense
Stock-based compensation expense	$ 43.1	$ 25.4	$ 4.4
Total estimated unrecognized compensation cost related to nonvested stock-based compensation arrangements	$ 16.7
Weighted average period recognized	1 year 4 months 24 days
Board of Director
Stock Based Compensation Expense
Stock-based compensation expense	$ 0.9	0.5	0.5
Restricted stock unit
Stock Based Compensation Expense
Stock-based compensation expense	12.6	9.7	9.7
Performance stock unit expense
Stock Based Compensation Expense
Stock-based compensation expense	24.5	1.2	$ (5.8)
Special Performance Stock Unit
Stock Based Compensation Expense
Stock-based compensation expense	$ 5.1	$ 14.0
Stock options \| 2013 Equity Incentive Plan
2013 Equity Incentive Plan
Number of shares authorized	15,000,000
Number of shares remaining available for grant	4,650,723
Class A common stock
Treasury Stock
Share repurchase program				200,000,000.0