Borrowings - JPM Credit Facility Narrative (Details) - USD ($) $ in Thousands			9 Months Ended
	Mar. 17, 2023	Sep. 13, 2022	Jun. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Debt			$ 3,168,906	$ 3,093,603
JPM Credit Facility
Debt Instrument [Line Items]
Debt			780,889
Revolving Credit Facility | JPM Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			1,487,500
Line of credit facility, increase (decrease), net			$ 512,500
Line of credit facility, commitment fee percentage			0.375%
Debt instrument, amortization period			1 year
Debt			$ 780,889	$ 692,592
Revolving Credit Facility | JPM Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Line of credit facility, interest rate during period	0.10%
Revolving Credit Facility | JPM Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Minimum
Debt Instrument [Line Items]
Line of credit facility, interest rate during period		0.11448%
Revolving Credit Facility | JPM Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Maximum
Debt Instrument [Line Items]
Line of credit facility, interest rate during period		0.42826%
Revolving Credit Facility | JPM Credit Facility | Line of Credit | Base Rate | Minimum
Debt Instrument [Line Items]
Line of credit facility, interest rate during period			1.75%
Revolving Credit Facility | JPM Credit Facility | Line of Credit | Base Rate | Maximum
Debt Instrument [Line Items]
Line of credit facility, interest rate during period			1.875%
Revolving Credit Facility | JPM Credit Facility, Portion Maturing February 11, 2026 | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 37,500
Letter of Credit | JPM Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 23,750