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Long-Term Debt - Senior Notes (Details)	9 Months Ended
Long-Term Debt - Senior Notes (Details)	Jun. 30, 2024 USD ($) d $ / shares	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Aug. 12, 2022 USD ($)
Debt Instrument
Payments of debt issuance costs and deferred financing fees	$ 19,900,000	$ 3,100,000
6.25% Senior Notes Maturing in February 2032 \| Senior Notes
Debt Instrument
Long-term Debt	$ 1,000,000,000		$ 0
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Proceeds from Issuance of Debt	$ 986,700,000
Payments of debt issuance costs and deferred financing fees	13,300,000
2.50% convertible senior notes \| Senior Notes
Debt Instrument
Long-term Debt	$ 575,000,000.0		$ 575,000,000.0	$ 575,000,000.0
Debt Instrument, Interest Rate, Stated Percentage	2.50%
Debt Instrument, Convertible, Conversion Ratio	9.4248
Debt Instrument, Convertible, Conversion Price \| $ / shares	$ 106.10
Debt Instrument, Convertible, Threshold Consecutive Trading Days \| d	5
Debt Instrument, Convertible, Threshold Trading Days \| d	10
Debt Instrument, Issued, Principal	$ 1,000
Debt Instrument, Convertible, Latest Date	Aug. 15, 2027
Debt Instrument, Convertible, Earliest Date	May 15, 2027
2.50% convertible senior notes \| Senior Notes \| Maximum
Debt Instrument
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	130.00%
2.50% convertible senior notes \| Senior Notes \| Minimum
Debt Instrument
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	98.00%