Loss and Loss Adjustment Expense Reserves (Tables)

6 Months Ended

Jun. 30, 2019

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)	2019		2018
Balance, Beginning of period	$	15,400.8	$	13,086.9
Less reinsurance recoverables on unpaid losses	2,572.7		2,170.1
Net balance, Beginning of period	12,828.1		10,916.8
Incurred related to:
Current year	11,687.1		10,164.6
Prior years	210.0		81.5
Total incurred	11,897.1		10,246.1
Paid related to:
Current year	6,407.5		5,533.7
Prior years	4,664.1		3,851.5
Total paid	11,071.6		9,385.2
Net balance, End of period	13,653.6		11,777.7
Plus reinsurance recoverables on unpaid losses	2,915.0		2,293.1
Balance, End of period	$	16,568.6	$	14,070.8