Amount of amortization expense attributable to debt issuance costs.

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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Long-Term Debt - Schedule of Maturities of Long-term Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Maturities of Long-term Debt [Abstract]
Total debt, carrying amount	$ 608.5
2021	326.3
2022	28.4
2023	253.8
Interest expense-amortization of deferred financing costs	2.0	$ 1.9	$ 1.8
Senior debt
Maturities of Long-term Debt [Abstract]
Total debt, carrying amount	308.5
2021	26.3
2022	28.4
2023	253.8
Convertible senior notes
Maturities of Long-term Debt [Abstract]
Total debt, carrying amount	300.0
2021	300.0
2022	0.0
2023	$ 0.0