Long-Term Debt - Schedule of Components of Long-Term Debt (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2022	Aug. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2020	Jun. 30, 2019	Aug. 31, 2017
Debt Instrument [Line Items]
Borrowings	$ 1,746,145,000	$ 1,650,576,000
Unamortized Deferred Issuance Costs / Discount	(12,720,000)	(9,743,000)
Net Carrying Value	1,733,425,000	1,640,833,000
Line of Credit
Debt Instrument [Line Items]
Borrowings	1,079,353,000	990,155,000
Unamortized Deferred Issuance Costs / Discount	(2,153,000)	(1,672,000)
Net Carrying Value	1,077,200,000	988,483,000
Convertible notes
Debt Instrument [Line Items]
Unamortized Deferred Issuance Costs / Discount				$ (1,000,000)
Trust Preferred Securities and Subordinated Notes
Debt Instrument [Line Items]
Borrowings	139,500,000
Unamortized Deferred Issuance Costs / Discount	(733,000)
Net Carrying Value	$ 138,767,000
Trust Preferred Securities and Subordinated Notes | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.25%
Trust preferred securities
Debt Instrument [Line Items]
Borrowings		139,500,000
Unamortized Deferred Issuance Costs / Discount		(779,000)
Net Carrying Value	$ 100,000,000	$ 138,721,000
Trust preferred securities | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.25%	2.25%
Facility A | Recourse Subordinate Securities Financing
Debt Instrument [Line Items]
Borrowings		$ 144,385,000
Unamortized Deferred Issuance Costs / Discount		(313,000)
Net Carrying Value		$ 144,072,000
Weighted Average Interest Rate (as a percent)		4.21%
Facility A | Recourse Subordinate Securities Financing | Affiliated Entity
Debt Instrument [Line Items]
Borrowings	$ 130,408,000
Unamortized Deferred Issuance Costs / Discount	0
Net Carrying Value	$ 130,408,000
Weighted Average Interest Rate (as a percent)	5.71%
Facility B | Recourse Subordinate Securities Financing
Debt Instrument [Line Items]
Borrowings		$ 102,351,000
Unamortized Deferred Issuance Costs / Discount		(353,000)
Net Carrying Value		$ 101,998,000
Weighted Average Interest Rate (as a percent)		4.21%
Facility B | Recourse Subordinate Securities Financing | Affiliated Entity
Debt Instrument [Line Items]
Borrowings	$ 101,706,000
Unamortized Deferred Issuance Costs / Discount	(50,000)
Net Carrying Value	$ 101,656,000
Weighted Average Interest Rate (as a percent)	4.21%
Facility C | Recourse Subordinate Securities Financing
Debt Instrument [Line Items]
Borrowings		$ 91,707,000
Unamortized Deferred Issuance Costs / Discount		(376,000)
Net Carrying Value		$ 91,331,000
Weighted Average Interest Rate (as a percent)		4.75%
Facility C | Recourse Subordinate Securities Financing | Affiliated Entity
Debt Instrument [Line Items]
Borrowings	$ 68,995,000
Unamortized Deferred Issuance Costs / Discount	(125,000)
Net Carrying Value	$ 68,870,000
Weighted Average Interest Rate (as a percent)	4.75%
Facility D | Line of Credit
Debt Instrument [Line Items]
Borrowings	$ 404,622,000	$ 307,215,000
Unamortized Deferred Issuance Costs / Discount	(667,000)	(507,000)
Net Carrying Value	403,955,000	306,708,000
Limit	$ 750,000,000	$ 400,000,000
Facility D | Line of Credit | SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.87%
Facility D | Line of Credit | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		2.75%
Facility E | Line of Credit
Debt Instrument [Line Items]
Borrowings	$ 308,933,000
Unamortized Deferred Issuance Costs / Discount	(838,000)
Net Carrying Value	308,095,000
Limit	$ 335,000,000	$ 400,000,000	$ 750,000,000		$ 600,000,000	$ 600,000,000
Facility E | Line of Credit | SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.25%
Facility F | Line of Credit
Debt Instrument [Line Items]
Borrowings	$ 64,689,000
Unamortized Deferred Issuance Costs / Discount	(473,000)
Net Carrying Value	64,216,000
Limit	$ 500,000,000
Facility F | Line of Credit | SOFR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.25%
Facility F | Line of Credit | SOFR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.50%
Facility G | Line of Credit
Debt Instrument [Line Items]
Borrowings		234,349,000
Unamortized Deferred Issuance Costs / Discount		(123,000)
Net Carrying Value		234,226,000
Limit		$ 450,000,000
Facility G | Line of Credit | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		2.21%
Facility H | Line of Credit
Debt Instrument [Line Items]
Borrowings		$ 110,148,000
Unamortized Deferred Issuance Costs / Discount		0
Net Carrying Value		110,148,000
Limit		$ 450,000,000
Facility H | Line of Credit | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		3.35%
5.625% convertible senior notes | Convertible notes
Debt Instrument [Line Items]
Borrowings	$ 150,200,000	$ 150,200,000
Unamortized Deferred Issuance Costs / Discount	(1,282,000)	(2,072,000)
Net Carrying Value	$ 148,918,000	$ 148,128,000
Weighted Average Interest Rate (as a percent)	5.625%	5.625%					5.625%	5.625%
5.75% exchangeable senior notes | Convertible notes
Debt Instrument [Line Items]
Borrowings	$ 162,092,000	$ 172,092,000
Unamortized Deferred Issuance Costs / Discount	(2,410,000)	(3,384,000)
Net Carrying Value	$ 159,682,000	$ 168,708,000
Weighted Average Interest Rate (as a percent)	5.75%	5.75%					5.75%
7.75% convertible senior notes | Convertible notes
Debt Instrument [Line Items]
Borrowings	$ 215,000,000
Unamortized Deferred Issuance Costs / Discount	(6,142,000)
Net Carrying Value	$ 208,858,000
Weighted Average Interest Rate (as a percent)	7.75%
4.75% convertible senior notes | Convertible notes
Debt Instrument [Line Items]
Borrowings	$ 199,000,000	$ 198,629,000	$ 199,000,000
Unamortized Deferred Issuance Costs / Discount		(1,836,000)
Net Carrying Value		$ 196,793,000
Weighted Average Interest Rate (as a percent)	4.75%	4.75%	4.75%						4.75%