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Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (I-K) (Details) $ in Thousands						3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 03, 2024 USD ($)	Sep. 30, 2024 USD ($) investment	Jun. 30, 2024 USD ($)	Dec. 18, 2023 USD ($) shares	Aug. 21, 2023 USD ($)	Sep. 30, 2024 USD ($) investment	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) investment	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) investment
Accounting Policies [Line Items]
Equity securities, FV-NI, unrealized gain (loss)						$ (25,748)	$ (72,583)	$ (217,370)	$ (77,710)
Equity securities, FV-NI, unrealized loss						63,674		287,043
Partnership investment interests								16,238		$ 35,196
Fair value assets		$ 411,500				411,500		411,500		1,241,817
Senior notes payable		1,529,560				1,529,560		1,529,560		1,668,021
Fair value		727,965				727,965		727,965		1,127,503
Notes payable, fair value disclosure		534,246				534,246		534,246		688,343
Realized gain (loss), foreign currency transaction, before tax						(1,836)	$ 322	231	$ (170)
Significant unobservable inputs (Level 3)
Accounting Policies [Line Items]
Fair value assets		$ 213,652				$ 213,652		$ 213,652		$ 985,000
Significant unobservable inputs (Level 3) \| Fair Value, Measurements, Recurring
Accounting Policies [Line Items]
Percentage of total assets measured in Level 3 of the hierarchy level		9.90%				9.90%		9.90%		16.20%
FRG Investment
Accounting Policies [Line Items]
Rate of equity interests					31.00%
B&W
Accounting Policies [Line Items]
Rate of equity interests		30.00%				30.00%		30.00%
Equity method investments, fair value disclosure		$ 55,991				$ 55,991		$ 55,991		$ 40,072
Synchronoss Technologies, Inc.
Accounting Policies [Line Items]
Rate of equity interests		7.00%				7.00%		7.00%
Equity method investments, fair value disclosure		$ 11,212				$ 11,212		$ 11,212		8,780
FRG
Accounting Policies [Line Items]
Purchase of equity investments					$ 281,144
Equity method investment, fair value adjustment		(63,674)						(509,761)
Equity method investments, fair value disclosure		0				0		0		287,043
FRG \| Subsequent Event
Accounting Policies [Line Items]
Equity method investment, fair value adjustment	$ 0
Other Equity Investments
Accounting Policies [Line Items]
Equity method investments, fair value disclosure		$ 50,595				$ 50,595		$ 50,595		$ 87,713
Equity method investment, number of private companies \| investment		5				5		5		6
Freedom VCM Holdings, LLC
Accounting Policies [Line Items]
Purchase of equity investments					216,500
Take-private transaction, vote or disposal, amount of shares					64,644
Repurchase amount					20,911
Equity method investments, fair value disclosure		$ 0				$ 0		$ 0		$ 232,065
Freedom VCM Holdings, LLC \| Conn’s
Accounting Policies [Line Items]
Sale of stock, percentage of ownership after transaction				49.99%
Proceeds			$ 69,900	$ 69,900
Freedom VCM Holdings, LLC \| Preferred Stock \| Conn’s
Accounting Policies [Line Items]
Consummated units (in shares) \| shares				1,000,000
Freedom VCM Holdings, LLC \| Nonvoting Common Stock \| Conn’s
Accounting Policies [Line Items]
Preferred stock, convertible, shares issuable \| shares				24,540,295
Freedom VCM Receivables, Inc. \| Related Party
Accounting Policies [Line Items]
Gain (loss) on sale of financing receivable					(78)
Payments to acquire finance receivables					$ 58,872
Interest rate					19.74%