Borrowings - JPM Credit Facility (Narrative) (Details) - USD ($)	Mar. 17, 2023	Sep. 13, 2022	Feb. 11, 2021	Mar. 31, 2025	Dec. 06, 2024	Dec. 05, 2024	Sep. 30, 2024
Debt Instrument [Line Items]
Long-term debt				$ 4,806,918,000			$ 4,599,430,000
JPM Credit Facility | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				1,997,500,000	$ 1,997,500,000	$ 1,822,500,000
Line of credit facility, commitment fee percentage			0.375%
Debt instrument, amortization period			1 year
Long-term debt				1,110,054,000			956,590,000
JPM Credit Facility | Revolving Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.10%
JPM Credit Facility | Revolving Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR) | Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		0.11448%
JPM Credit Facility | Revolving Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR) | Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		0.42826%
JPM Credit Facility | Revolving Credit Facility | Line of Credit | Base Rate | Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.75%
JPM Credit Facility | Revolving Credit Facility | Line of Credit | Base Rate | Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.875%
JPM Credit Facility | Letter of Credit | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 23,750,000
Long-term debt				$ 0			$ 0