Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Mar. 19, 2014
Convertible Subordinated Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate percentage	2.75%	2.75%
Long-term debt measured at fair value	$ 2.9
Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt measured at fair value	$ 422.3