RESERVE FOR LOSSES AND LOSS EXPENSES (Tables)

3 Months Ended

Mar. 31, 2025

Insurance [Abstract]

Summary of Reconciliation of Beginning and Ending Gross Reserve for Losses and Loss Expenses and Net Reserve for Unpaid Losses and Loss Expenses

The following table presents a reconciliation of the Company's beginning and ending gross reserve for losses and loss expenses and net reserve for unpaid losses and loss expenses:

	Three months ended March 31,
	2025		2024
Gross reserve for losses and loss expenses, beginning of period	$	17,218,929	$	16,434,018
Less reinsurance recoverable on unpaid losses and loss expenses, beginning of period	(6,840,897)		(6,323,083)
Net reserve for unpaid losses and loss expenses, beginning of period	10,378,032		10,110,935
Net incurred losses and loss expenses related to:
Current year	803,862		728,671
Prior years	(17,937)		—
	785,925		728,671
Net paid losses and loss expenses related to:
Current year	(45,288)		(50,724)
Prior years	(723,513)		(612,571)
	(768,801)		(663,295)
Foreign exchange and other	149,785		(48,602)
Net reserve for unpaid losses and loss expenses, end of period	10,544,941		10,127,709
Reinsurance recoverable on unpaid losses and loss expenses, end of period	6,944,518		6,503,188
Gross reserve for losses and loss expenses, end of period	$	17,489,459	$	16,630,897

Summary of Prior Year Loss Development

The following table presents net favorable (adverse) prior year reserve development by segment:

	Three months ended March 31,
	2025		2024
	Favorable (Adverse)		Favorable (Adverse)
Insurance	$	13,978	$	—
Reinsurance	3,959		—
Total	$	17,937	$	—

Prior year reserve development by reserve class was as follows:

	Three months ended March 31,
	2025		2024
	Favorable (Adverse)		Favorable (Adverse)
Property	$	9,996	$	8,011
Casualty	—		—
Specialty other	3,982		(8,011)
Total	$	13,978	$	—

Prior year reserve development by reserve class was as follows:

	Three months ended March 31,
	2025		2024
	Favorable (Adverse)		Favorable (Adverse)
Casualty	$	—	$	—
Specialty	3,834		—
Run-off	125		—
Total	$	3,959	$	—

Summary of the Lines of Business Categories by Reserve Class

The following table maps the Company's lines of business to reserve classes:

Insurance segment
	Reserve class
	Property	Casualty	Specialty other
Reported lines of business
Property	X
Professional lines		X
Liability		X
Cyber		X
Marine and aviation			X
Accident and health			X
Credit and political risk			X

The following table maps the Company's lines of business to reserve classes:

Reinsurance segment
	Reserve class
	Casualty	Specialty	Run-off
Reported lines of business
Liability	X
Professional lines	X
Motor	X
Accident and health		X
Credit and surety		X
Agriculture		X
Marine and aviation		X
Catastrophe			X
Property			X
Engineering			X