Loss and Loss Adjustment Expense Reserves (Tables)

6 Months Ended

Jun. 30, 2024

Loss and Loss Adjustment Expenses Reserves [Abstract]

Schedule of Liability for Unpaid Claims and Claims Adjustment Expense

Activity in the loss and loss adjustment expense reserves is summarized as follows:

	June 30,
(millions)	2024		2023
Balance at January 1	$	34,389.2	$	30,359.3
Less reinsurance recoverables on unpaid losses	4,789.0		5,559.2
Net balance at January 1	29,600.2		24,800.1
Incurred related to:
Current year	23,629.4		21,683.6
Prior years	(62.5)		1,110.5
Total incurred	23,566.9		22,794.1
Paid related to:
Current year	11,470.3		10,789.5
Prior years	9,606.6		9,115.8
Total paid	21,076.9		19,905.3
Net balance at June 30	32,090.2		27,688.9
Plus reinsurance recoverables on unpaid losses	4,515.0		5,064.4
Balance at June 30	$	36,605.2	$	32,753.3