Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Summary of Deferred Policy Acquisition Cost Amortization and Net Advertising Expense

The table below presents a summary of deferred policy acquisition cost amortization and net advertising expense:

	Year Ended December 31,
	2022		2021		2020
	(Amounts in millions)
Deferred policy acquisition cost amortization	$	654.6	$	633.4	$	627.8
Net advertising expense	11.8		50.1		37.7

Effects of Reinsurance

The effect of reinsurance on property and casualty premiums written and earned was as follows:

	Year Ended December 31,
	2022		2021		2020
	(Amounts in thousands)
Premiums Written
Direct	$	4,018,057	$	3,877,476	$	3,624,965
Ceded	(81,256)		(65,521)		(50,630)
Assumed	10,743		13,361		8,012
Net	$	3,947,544	$	3,825,316	$	3,582,347
Premiums Earned
Direct	$	3,993,771	$	3,764,626	$	3,574,898
Ceded	(80,950)		(65,017)		(56,212)
Assumed	10,821		13,301		8,067
Net	$	3,923,642	$	3,712,910	$	3,526,753

Premium Receivable, Allowance for Credit Loss

The following table presents a summary of changes in allowance for credit losses on premiums receivable:

	Year Ended December 31,
	2022		2021		2020
Beginning balance	$	6,000	$	10,000	$	1,445
Cumulative effect of adopting ASU 2016-13	—		—		1,855
Beginning balance, as adjusted	6,000		10,000		3,300
Provision during the period for expected credit losses	4,213		(893)		10,294
Write-off amounts during the period	(5,027)		(3,693)		(4,406)
Recoveries during the period of amounts previously written off	614		586		812
Ending balance	$	5,800	$	6,000	$	10,000