Debt - Narrative (Details) € in Millions			1 Months Ended					3 Months Ended				6 Months Ended		9 Months Ended
	Apr. 29, 2022 USD ($)	Sep. 08, 2021 USD ($)	Jul. 31, 2023	Sep. 30, 2021 USD ($)	Aug. 31, 2021	Jul. 31, 2021	Mar. 31, 2007 USD ($)	Sep. 30, 2024 USD ($) credit_facility	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023	Sep. 30, 2024 USD ($) credit_facility	Sep. 30, 2023 USD ($)	Sep. 30, 2024 EUR (€) credit_facility	Sep. 17, 2024 USD ($)	Aug. 22, 2024 USD ($)	Jul. 31, 2024	Jun. 28, 2024 USD ($)	Sep. 30, 2022 USD ($)	Jun. 16, 2022 USD ($)	Apr. 30, 2022 USD ($)	Dec. 31, 2021 USD ($) letterOfCredit	Aug. 11, 2021 USD ($)	Jul. 13, 2021 USD ($)	Jul. 13, 2021 EUR (€)	Mar. 23, 2021 USD ($)
Debt Instrument
Repayments of notes														$ 36,700,000	$ 24,300,000
Subsidiary - HG Global | Interest Rate Cap
Debt Instrument
Notional amount																		$ 150,000,000				$ 150,000,000
Maximum interest rate																		10.76%				9.76%
Kudu | Interest Rate Cap
Debt Instrument
Notional amount																	$ 150,000,000
Maximum interest rate																	8.95%
Ark 2007 Subordinated Notes | Junior Subordinated Debt
Debt Instrument
Face value							$ 30,000,000
Repayments of notes									$ 30,000,000
Ark 2007 Subordinated Notes | Junior Subordinated Debt | London Interbank Offered Rate (LIBOR)
Debt Instrument
Basis spread on variable rate							4.60%
Ark 2021 Subordinated Notes | Subordinated Debt
Debt Instrument
Face value				$ 163,300,000							$ 163,300,000
Proceeds from debt, net of debt issuance costs											$ 157,800,000
Ark 2021 Subordinated Notes Tranche 1 | Subordinated Debt
Debt Instrument
Face value																										$ 46,300,000	€ 39.1
Amount borrowed								$ 43,600,000				$ 42,700,000		43,600,000		€ 39.1
Ark 2021 Subordinated Notes Tranche 1 | Subordinated Debt | Euro Interbank Offered Rate (EURIBOR)
Debt Instrument
Basis spread on variable rate						5.75%
Ark 2021 Subordinated Notes Tranche 2 | Subordinated Debt
Debt Instrument
Face value																									$ 47,000,000
Amount borrowed								47,000,000.0				47,000,000.0		47,000,000.0
Ark 2021 Subordinated Notes Tranche 2 | Subordinated Debt | London Interbank Offered Rate (LIBOR)
Debt Instrument
Basis spread on variable rate					5.75%
Kudu Credit Facility | Secured Debt
Debt Instrument
Face value																				$ 350,000,000								$ 300,000,000
Basis spread on variable rate			0.26%										0.25%
Repayments of notes								0		$ 0				0	$ 16,900,000
Amount borrowed								225,300,000				210,300,000		225,300,000
Stated margin			4.30%										4.30%						4.45%
Restricted cash								$ 14,800,000				$ 14,900,000		$ 14,800,000
Debt covenant, maximum loan to value percent								23.70%						23.70%		23.70%
Percentage of borrowing base								35.00%						35.00%		35.00%
Kudu Credit Facility | Secured Debt | Debt Covenant, Period 1
Debt Instrument
Debt covenant, loan to value percent								50.00%						50.00%		50.00%
Kudu Credit Facility | Secured Debt | Debt Covenant, Period 2
Debt Instrument
Debt covenant, loan to value percent								40.00%						40.00%		40.00%
Kudu Credit Facility | Secured Debt | Debt Covenant, Period 3
Debt Instrument
Debt covenant, loan to value percent								25.00%						25.00%		25.00%
Kudu Credit Facility | Secured Debt | Debt Covenant, Period 4
Debt Instrument
Debt covenant, loan to value percent								15.00%						15.00%		15.00%
Kudu Credit Facility | Secured Debt | Debt Covenant, Period 5
Debt Instrument
Debt covenant, loan to value percent								0.00%						0.00%		0.00%
Kudu Credit Facility | Secured Debt | Secured Overnight Financing Rate (SOFR)
Debt Instrument
Basis spread on variable rate												0.26%
Ark 2021 Subordinated Notes Tranche 3 | Subordinated Debt
Debt Instrument
Face value		$ 70,000,000
Debt instrument, period for interest rate increase		10 years
Additional interest rate														1.00%
Solvency capital requirement				120.00%
Debt to capital requirement				40.00%
Amount borrowed								$ 70,000,000.0				$ 70,000,000.0		$ 70,000,000.0
Ark 2021 Subordinated Notes Tranche 3 | Subordinated Debt | London Interbank Offered Rate (LIBOR)
Debt Instrument
Basis spread on variable rate		6.10%
ING LOC Facility | Line of Credit | Letter of Credit
Debt Instrument
Number of letter of credit agreements | letterOfCredit																								2
Total commitment under revolving credit facility																								$ 50,000,000
Citibank LOC Facility | Line of Credit | Letter of Credit
Debt Instrument
Total commitment under revolving credit facility																								$ 125,000,000
Letters of credit outstanding								107,900,000						107,900,000
Pledged collateral								141,300,000						141,300,000
Lloyds LOC Facility | Line of Credit | Letter of Credit
Debt Instrument
Total commitment under revolving credit facility																					$ 100,000,000
Letters of credit outstanding								35,500,000						35,500,000
Pledged collateral								66,900,000						$ 66,900,000
HG Global Senior Notes | Senior Notes
Debt Instrument
Face value	$ 150,000,000
Additional interest rate														1.00%
Amount borrowed								150,000,000.0				150,000,000.0		$ 150,000,000.0
Stated margin	6.00%
Anniversary of funding date	5 years
Annual payments																							$ 15,000,000
Interest accrued multiplier																						8
Interest reserve account, maximum																						$ 29,300,000
Interest reserve account								29,300,000				30,400,000		29,300,000
HG Global Senior Notes | Senior Notes | Secured Overnight Financing Rate (SOFR)
Debt Instrument
Basis spread on variable rate	0.26%
Other Operations debt | Secured Debt
Debt Instrument
Amount borrowed								$ 22,600,000				$ 28,900,000		$ 22,600,000
Secured credit facilities | credit_facility								4						4		4