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Debt and Liquidity (2020 Senior Secured Notes) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Sep. 30, 2023
2023 Senior Secured Notes
Debt Instrument [Line Items]
Debt Instrument, Event Of Default, Percentage Of Debt Held	30.00%
2020 Senior Secured Notes
Debt Instrument [Line Items]
Debt Instrument, Event Of Default, Percentage Of Debt Held	30.00%
Secured Notes
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt instrument, interest rate, stated percentage	4.625%
Secured Notes | 2023 Senior Secured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	9.875%	9.875%
Debt Instrument, Covenant, Restricted Payments Allowable With No Default Or Event Of Default, Pro Forma Consolidated First Lien Net Leverage Ratio, Maximum	2.00
Debt Instrument, Covenant, Restricted Payments Allowable Pursuant To Certain Baskets, Pro Forma Consolidated First Lien Net Leverage Ratio, Maximum	2.00
Secured Notes | 2020 Senior Secured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.625%
Debt Instrument, Covenant, Restricted Payments Allowable With No Default Or Event Of Default, Pro Forma Consolidated First Lien Net Leverage Ratio, Maximum	2.00
Debt Instrument, Covenant, Restricted Payments Allowable Pursuant To Certain Baskets, Pro Forma Consolidated First Lien Net Leverage Ratio, Maximum	2.00
Secured Notes | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	40.00%
Secured Notes | Debt Instrument, Redemption, Period One | 2023 Senior Secured Notes
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	109.875%
Debt Instrument, Redemption Price, Premium Applicable, Percentage	100.00%

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