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Borrowings - Unsecured Notes (Details) - USD ($) $ in Thousands												3 Months Ended		9 Months Ended
	Jul. 14, 2022	Jun. 15, 2022	Mar. 08, 2021	Feb. 16, 2021	Jan. 29, 2021	Apr. 30, 2019	Sep. 25, 2018	Jul. 05, 2018	Jan. 30, 2018	Jun. 30, 2017	May 06, 2016	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Oct. 17, 2018	Sep. 30, 2016
Debt Instrument [Line Items]
Face amount												$ 300,000		$ 300,000
Repayment of Unsecured Notes														55,000	$ 141,750
Amortization of financing costs														5,082	5,660
Unsecured Notes outstanding balance												531,500		531,500		$ 511,500
Unsecured Notes
Debt Instrument [Line Items]
Interest expense												6,512	$ 5,958	18,624	18,443
Amortization of financing costs												$ 202	$ 204	$ 607	$ 1,661
Weighted average interest rate												4.80%	4.70%	4.70%	4.70%
Effective interest rate												5.00%	4.80%	4.90%	5.20%
Average debt outstanding												$ 539,870	$ 511,500	$ 525,456	$ 518,333
Unsecured Notes | Minimum
Debt Instrument [Line Items]
Face amount												$ 150,000		$ 150,000
2016 Unsecured Notes
Debt Instrument [Line Items]
Repayment of Unsecured Notes				$ 90,000
2016 Unsecured Notes | Unsecured Notes
Debt Instrument [Line Items]
Face amount											$ 50,000							$ 40,000
Term of debt											5 years
Stated interest rate											5.313%
2017A Unsecured Notes
Debt Instrument [Line Items]
Repayment of Unsecured Notes	$ 55,000
2017A Unsecured Notes | Unsecured Notes
Debt Instrument [Line Items]
Face amount										$ 55,000
Term of debt										5 years
Stated interest rate										4.76%
2018A Unsecured Notes | Unsecured Notes
Debt Instrument [Line Items]
Face amount									$ 90,000
Term of debt									5 years
Stated interest rate									4.87%
2018B Unsecured Notes | Unsecured Notes
Debt Instrument [Line Items]
Face amount								$ 50,000
Term of debt								5 years
Stated interest rate								5.36%
2019A Unsecured Notes | Unsecured Notes
Debt Instrument [Line Items]
Face amount						$ 116,500
Term of debt						5 years
Stated interest rate						5.494%
2021A Unsecured Notes | Unsecured Notes
Debt Instrument [Line Items]
Face amount					$ 200,000
Term of debt					5 years
Stated interest rate					3.875%
2022A Unsecured Notes | Unsecured Notes
Debt Instrument [Line Items]
Face amount		$ 75,000
Term of debt		5 years
Stated interest rate		5.90%
5.75% Unsecured Notes | Unsecured Notes
Debt Instrument [Line Items]
Face amount							$ 50,000										$ 1,750
Term of debt							5 years
Stated interest rate							5.75%
Redemption of principal			$ 51,750
Redemption as a percentage of principal			100.00%

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