Debt - Narrative (Details) shares in Thousands		1 Months Ended				3 Months Ended		6 Months Ended	9 Months Ended
		Oct. 31, 2023 USD ($)	Jun. 30, 2023 USD ($) shares	Feb. 28, 2023 USD ($)	Jan. 31, 2023 USD ($) unsecuredRevolvingCreditFacility	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Aug. 31, 2023
Long-Term Debt
Convertible notes settlement									$ 12,189,000
Loss on extinguishment of debt									$ 81,441,000	$ 16,449,000
Minimum | Contract With Customer, Liability, Up-Front Payment Arrangement
Long-Term Debt
Credit agency fees, percentage of loan amount payable									2.35%
Maximum | Contract With Customer, Liability, Up-Front Payment Arrangement
Long-Term Debt
Credit agency fees, percentage of loan amount payable									5.48%
Convertible notes | Minimum
Long-Term Debt
Interest rate	[1]					2.88%			2.88%
Convertible notes | Maximum
Long-Term Debt
Interest rate	[1]					6.00%			6.00%
Convertible notes | Convertible Senior Notes 4.25 Due 2023
Long-Term Debt
Outstanding balance			$ 350,000,000				$ 350,000,000	$ 350,000,000
Interest rate			4.25%				4.25%	4.25%
Convertible notes cash settlement			$ 337,800,000				$ 337,800,000	$ 337,800,000
Convertible notes shares issued (in shares) | shares			374
Convertible notes settlement			$ 12,200,000
Convertible notes | Convertible Senior Notes 2.875 Due 2023
Long-Term Debt
Interest rate											2.875%
Unsecured senior notes | Minimum
Long-Term Debt
Interest rate	[1]					3.70%			3.70%
Unsecured senior notes | Maximum
Long-Term Debt
Interest rate	[1]					11.63%			11.63%
Unsecured senior notes | Senior Guaranteed Notes Due January 2030
Long-Term Debt
Interest rate				7.25%
Face amount				$ 700,000,000
Unsecured term loans | Minimum
Long-Term Debt
Interest rate	[1]					1.28%			1.28%
Unsecured term loans | Maximum
Long-Term Debt
Interest rate	[1]					5.89%			5.89%
Unsecured term loans | Novation Agreement
Long-Term Debt
Interest rate			4.21%				4.21%	4.21%
Debt instrument, term			12 years
Proceeds from unsecured debt			$ 503,200,000
Unsecured term loans | Novation Agreement | Euler Hermes
Long-Term Debt
Percentage of unsecured term loan guaranteed by an export credit agency			95.00%
Secured senior notes | Minimum
Long-Term Debt
Interest rate	[1]					8.25%			8.25%
Secured senior notes | Maximum
Long-Term Debt
Interest rate	[1]					11.50%			11.50%
Secured senior notes | Senior Secured Notes Due 2025
Long-Term Debt
Interest rate			11.50%				11.50%	11.50%
Repayment of debt			$ 392,000,000			$ 500,000,000
Loss on extinguishment of debt						37,900,000	$ 30,200,000	$ 30,200,000
Secured senior notes | Senior Secured Notes Due 2025 | Forecast
Long-Term Debt
Interest rate		11.50%
Redemption amount		$ 500,000,000
Revolving Credit Facility
Long-Term Debt
Number of unsecured revolving credit facilities | unsecuredRevolvingCreditFacility					2
Revolving Credit Facility | Line of Credit
Long-Term Debt
Maximum borrowing capacity						3,000,000,000			$ 3,000,000,000
Remaining borrowing capacity						$ 2,700,000,000			$ 2,700,000,000
Revolving Credit Facility | Line of Credit | Revolving Credit Facility, $2.3 billion
Long-Term Debt
Proceeds from credit facility					$ 2,300,000,000
Extension term					1 year
Revolving Credit Facility | Line of Credit | Unsecured Term Loan Due October 2024 | Forecast
Long-Term Debt
Maximum borrowing capacity		501,600,000
Revolving Credit Facility | Line of Credit | Revolving Credit Facility, Aggregate Commitment | Forecast
Long-Term Debt
Maximum borrowing capacity		3,500,000,000
Revolving Credit Facility | Line of Credit | Aggregate Revolving Capacity, October 2028 | Forecast
Long-Term Debt
Maximum borrowing capacity		1,600,000,000
Revolving Credit Facility | Line of Credit | Aggregate Revolving Capacity, October 2026 | Forecast
Long-Term Debt
Maximum borrowing capacity		1,600,000,000
Revolving Credit Facility | Line of Credit | Aggregate Revolving Capacity, April 2025 | Forecast
Long-Term Debt
Maximum borrowing capacity		$ 242,500,000
Line of Credit | Term Loan Facility, $700 Million
Long-Term Debt
Debt terminated				$ 700,000,000
Debt instrument, term				364 days
Line of Credit | Senior Unsecured Note, Backstop Committed Financing
Long-Term Debt
Debt terminated				$ 350,000,000

[1] Interest rates based on outstanding loans as of September 30, 2023, and for variable rate debt include either LIBOR, EURIBOR or Term SOFR plus the applicable margin.