Reserves for Losses and Loss Adjustment Expenses (Average Annual Percentage Payout of Incurred Claims) (Details)	Dec. 31, 2022
Commercial Accounts business unit [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Average annual percentage payout of incurred claims, year one	43.60%
Average annual percentage payout of incurred claims, year two	25.50%
Average annual percentage payout of incurred claims, year three	10.50%
Average annual percentage payout of incurred claims, year four	9.10%
Average annual percentage payout of incurred claims, year five	4.90%
Average annual percentage payout of incurred claims, year six	2.60%
Average annual percentage payout of incurred claims, year seven	1.90%
Average annual percentage payout of incurred claims, year eight	1.00%
Average annual percentage payout of incurred claims, year nine	0.70%
Average annual percentage payout of incurred claims, year ten	0.20%
General Aviation and Satellite Component [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Average annual percentage payout of incurred claims, year one	64.20%
Average annual percentage payout of incurred claims, year two	21.60%
Average annual percentage payout of incurred claims, year three	5.20%
Average annual percentage payout of incurred claims, year four	4.70%
Average annual percentage payout of incurred claims, year five	3.00%
Average annual percentage payout of incurred claims, year six	1.00%
Average annual percentage payout of incurred claims, year seven	0.20%
Average annual percentage payout of incurred claims, year eight	0.10%
Average annual percentage payout of incurred claims, year nine	0.00%
Average annual percentage payout of incurred claims, year ten	0.00%
Personal Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Average annual percentage payout of incurred claims, year one	60.60%
Average annual percentage payout of incurred claims, year two	27.20%
Average annual percentage payout of incurred claims, year three	7.50%
Average annual percentage payout of incurred claims, year four	3.60%
Average annual percentage payout of incurred claims, year five	0.80%
Average annual percentage payout of incurred claims, year six	0.20%
Average annual percentage payout of incurred claims, year seven	0.10%
Average annual percentage payout of incurred claims, year eight	0.00%
Average annual percentage payout of incurred claims, year nine	0.00%
Average annual percentage payout of incurred claims, year ten	0.00%
Runoff Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Average annual percentage payout of incurred claims, year one	26.90%
Average annual percentage payout of incurred claims, year two	22.30%
Average annual percentage payout of incurred claims, year three	20.90%
Average annual percentage payout of incurred claims, year four	14.20%
Average annual percentage payout of incurred claims, year five	8.50%
Average annual percentage payout of incurred claims, year six	3.40%
Average annual percentage payout of incurred claims, year seven	1.70%
Average annual percentage payout of incurred claims, year eight	1.10%
Average annual percentage payout of incurred claims, year nine	0.60%
Average annual percentage payout of incurred claims, year ten	0.40%