INDEBTEDNESS AND BORROWING FACILITY - Summary of Long-term Debt (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
INDEBTEDNESS
Total principal amount	$ 437.3		$ 459.9
Less unamortized discount and debt issuance costs	(2.6)		(3.0)
Total long-term debt	434.7		456.9
Estimated fair value of long-term debt	184.7		317.2
Gain on extinguishment of debt, net	2.0	$ 0.5
Term Loan
INDEBTEDNESS
Total principal amount	67.4		90.0
Principal amount repaid	22.6
Gain on extinguishment of debt, net	2.0
2022 Senior notes
INDEBTEDNESS
Total principal amount	$ 369.9		$ 369.9

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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Gross amount of debt extinguished.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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