Basis of Presentation (Tables)

3 Months Ended

Mar. 31, 2021

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Premium Receivable, Allowance for Credit Loss

The following table summarizes changes in our allowance for credit loss exposure on our premiums receivables for the year-to-date periods ending:

(millions)	March 31, 2021		March 31, 2020		December 31, 2020
Allowance for credit loss, beginning of period	$	356.2	$	283.2	$	283.2
Increase in allowance1	60.9		170.3		472.0
Write-offs2	(151.8)		(108.8)		(399.0)
Allowance for credit loss, end of period	$	265.3	$	344.7	$	356.2

1Represents the incremental increase in other underwriting expenses.

2Represents portion of allowance that is reversed when premiums receivables are written off.