Schedule VI - Supplementary Information For Property and Casualty Insurance Underwriters (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Net Losses and Loss Adjustment Expenses Incurred Related to Current Year	$ 5,798,528	$ 4,940,987	$ 4,851,051
Net Losses and Loss Adjustment Expenses Incurred Related to Prior Years	(771,011)	(356,184)	(161,452)
Consolidated Subsidiaries
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Deferred Acquisition Costs	1,263,870	901,841	790,708
Reserves for Losses and Loss Adjustment Expenses	20,031,943	17,757,156	16,513,929
Discount, if any, deducted in Column C	60,536	55,575	23,326
Unearned Premiums	7,337,002	6,011,942	4,838,965
Net Premiums Earned	9,678,077	8,082,298	6,991,935
Net investment income	496,547	389,118	519,608
Net Losses and Loss Adjustment Expenses Incurred Related to Current Year	5,798,528	4,940,987	4,851,051
Net Losses and Loss Adjustment Expenses Incurred Related to Prior Years	(771,011)	(356,184)	(161,452)
Amortization of Deferred Acquisition Costs	1,739,580	1,303,178	1,004,842
Net Paid Losses and Loss Adjustment Expenses	3,141,948	2,826,551	2,661,117
Net Premiums Written	$ 11,077,189	$ 9,018,337	$ 7,437,716