Schedule VI. Supplementary Insurance Information Concerning Property-Casualty Insurance Operations (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]
Current year	$ 4,586,422	$ 4,125,557	$ 3,108,421
Prior years	(247,582)	(249,470)	(183,812)
Consolidated Subsidiaries
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Deferred Policy Acquisition Costs	1,171,738	849,160	633,521
Reserves for Unpaid Claims and Claim Adjustment Expenses	15,892,573	13,294,630	10,381,138
Discount, if any, Deducted	0	0	0
Unearned Premiums	4,559,107	3,531,213	2,763,599
Earned Premiums	6,333,989	5,194,181	3,952,462
Net Investment Income	559,932	319,479	354,038
Current year	4,586,422	4,125,557	3,108,421
Prior years		(249,470)	(183,812)
Amortization of Deferred Policy Acquisition Costs	1,568,606	1,214,858	897,677
Paid Claims and Claim Adjustment Expenses	2,030,156	2,224,102	2,004,628
Net Premiums Written	$ 7,196,160	$ 5,939,375	$ 4,096,333