Long-Term Debt - Senior Notes (Details) - Senior Notes	9 Months Ended
Jun. 30, 2026 USD ($) d $ / shares	Sep. 30, 2025 USD ($)
2.50% convertible senior notes
Debt Instrument
Long-term Debt	$ 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, Earliest Date	May 15, 2027
Debt Instrument, Convertible, Latest Date	Aug. 15, 2027
2.50% convertible senior notes \| Maximum
Debt Instrument
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	130.00%
2.50% convertible senior notes \| Minimum
Debt Instrument
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	98.00%
6.50% Senior Notes Maturing March 2036
Debt Instrument
Long-term Debt	$ 1,300,000,000	0
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Proceeds from Issuance of Debt	$ 1,284,700,000
Debt Issuance Costs, Gross	15,300,000
6.250% Senior Notes Maturing in October 2034
Debt Instrument
Long-term Debt	1,200,000,000	$ 600,000,000.0
Additional Issuance of 4.625% Senior Note Maturing in October 2034
Debt Instrument
Long-term Debt, Additional Proceeds	$ 600,000,000.0
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Proceeds from Issuance of Debt	$ 600,400,000
Debt Issuance Costs, Gross	$ 4,100,000
Debt Instrument, Issuance Price, Percentage of Par Value	100.75%

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-14

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