Debt and Liquidity (Summary of Long-Term Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Debt Instrument [Line Items]
Unamortized debt discount and issuance costs	$ (21,957)	$ (24,494)
Total debt	928,178	925,645
Less: Long-term debt, current portion	(132)	(134)
Long-term debt	928,046	925,511
Secured Notes | 2020 Senior Secured Notes
Debt Instrument [Line Items]
Long-term debt, gross	500,000	500,000
Secured Notes | 2023 Senior Secured Notes
Debt Instrument [Line Items]
Long-term debt, gross	450,000	450,000	$ 450,000
Other debt
Debt Instrument [Line Items]
Long-term debt, gross	$ 135	$ 139