Loss and Loss Adjustment Expense Reserves (Tables)

9 Months Ended

Sep. 30, 2023

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:

	September 30,
(millions)	2023		2022
Balance at January 1	$	30,359.3	$	26,164.1
Less reinsurance recoverables on unpaid losses	5,559.2		4,733.6
Net balance at January 1	24,800.1		21,430.5
Incurred related to:
Current year	33,035.0		28,245.4
Prior years	1,147.0		52.8
Total incurred	34,182.0		28,298.2
Paid related to:
Current year	18,581.3		15,712.4
Prior years	11,764.7		9,418.5
Total paid	30,346.0		25,130.9
Net balance at September 30	28,636.1		24,597.8
Plus reinsurance recoverables on unpaid losses	4,941.2		6,034.0
Balance at September 30	$	33,577.3	$	30,631.8