Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
2017 Senior Notes | 2017 Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 504.9	$ 495.0
Convertible Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value		69.1
Term Loan B
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 419.7	$ 425.0