Reinsurance and Retention Limits (Tables)

12 Months Ended

Dec. 31, 2023

Reinsurance and Retention Limits [Abstract]

Reinsurance Ceded and Other Related Data

Years Ended December 31:		2023		2022		2021
General Insurance
Written premiums:	Direct	$	6,776.4	$	6,263.3	$	5,691.3
	Assumed	96.6		90.0		74.0
	Ceded	$	2,516.7	$	2,375.1	$	2,084.4
Earned premiums:	Direct	$	6,513.2	$	6,021.0	$	5,509.1
	Assumed	94.7		87.1		73.7
	Ceded	$	2,488.6	$	2,299.5	$	2,027.3
Losses ceded		$	1,795.9	$	1,677.3	$	1,255.6