Credit Facilities (Summary Of Outstanding Letters Of Credit And Borrowings) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	May 05, 2021	Feb. 23, 2021
Line of Credit Facility [Line Items]
Capacity	$ 1,200,000,000
Bermuda Re Wells Fargo Bank Bilateral Letter of Credit Facility [Member]
Line of Credit Facility [Line Items]
Capacity	500,000,000	$ 500,000,000	$ 500,000,000	$ 50,000,000
In Use	435,000,000	351,000,000
Bermuda Re Wells Fargo Bank Bilateral Letter of Credit Facility One [Member]
Line of Credit Facility [Line Items]
Capacity	500,000,000	500,000,000
In Use	$ 387,000,000	$ 351,000,000
Date of Expiry	Dec. 30, 2022	Dec. 30, 2022
Bermuda Re Wells Fargo Bank Bilateral Letter of Credit Facility Two [Member]
Line of Credit Facility [Line Items]
In Use	$ 47,000,000
Date of Expiry		Dec. 29, 2023
Bermuda Re Citibank LOC Facility [Member]
Line of Credit Facility [Line Items]
Capacity	370,000,000	$ 370,000,000
In Use	322,000,000	333,000,000
Bermuda Re Citibank LOC Facility One [Member]
Line of Credit Facility [Line Items]
Capacity	230,000,000	230,000,000
In Use	$ 201,000,000	$ 4,000,000
Date of Expiry	Dec. 31, 2022	Feb. 28, 2022
Bermuda Re Citibank LOC Facility Two [Member]
Line of Credit Facility [Line Items]
In Use	$ 1,000,000	$ 1,000,000
Date of Expiry	Jan. 21, 2023	Mar. 01, 2022
Bermuda Re Citibank LOC Facility Three [Member]
Line of Credit Facility [Line Items]
In Use	$ 4,000,000	$ 1,000,000
Date of Expiry	Feb. 28, 2023	Nov. 24, 2022
Bermuda Re Citibank LOC Facility Four [Member]
Line of Credit Facility [Line Items]
In Use	$ 1,000,000
Date of Expiry	Mar. 01, 2023	Dec. 16, 2022
Bermuda Re Citibank LOC Facility Five [Member]
Line of Credit Facility [Line Items]
In Use	$ 3,000,000	$ 217,000,000
Date of Expiry	Sep. 23, 2023	Dec. 31, 2022
Bermuda Re Citibank LOC Facility Six [Member]
Line of Credit Facility [Line Items]
In Use		$ 1,000,000
Date of Expiry	Dec. 20, 2023	Aug. 15, 2023
Bermuda Re Citibank LOC Facility Seven [Member]
Line of Credit Facility [Line Items]
In Use	$ 6,000,000	$ 1,000,000
Date of Expiry	Dec. 31, 2023	Sep. 23, 2023
Bermuda Re Citibank LOC Facility Eight [Member]
Line of Credit Facility [Line Items]
In Use	$ 20,000,000	$ 23,000,000
Date of Expiry	Sep. 30, 2026	Dec. 30, 2025
Bermuda Re Citibank LOC Facility - Uncommitted [Member]
Line of Credit Facility [Line Items]
Capacity	$ 140,000,000	$ 140,000,000
In Use	$ 84,000,000	$ 84,000,000
Date of Expiry	Dec. 31, 2022	Dec. 31, 2022
Bermuda Re Bayerische Landesbank Bilateral Letter of Credit Facility [Member]
Line of Credit Facility [Line Items]
Capacity	$ 200,000,000	$ 200,000,000
In Use	$ 153,000,000	$ 155,000,000
Date of Expiry	Dec. 31, 2022	Dec. 31, 2022
Bermuda Re Lloyd's Bank Credit Facility [Member]
Line of Credit Facility [Line Items]
Capacity	$ 250,000,000	$ 50,000,000
In Use	131,000,000	46,000,000
Bermuda Re Lloyd's Bank Credit Facility One [Member]
Line of Credit Facility [Line Items]
Capacity	50,000,000	50,000,000
In Use	$ 46,000,000	$ 46,000,000
Date of Expiry	Dec. 31, 2022	Dec. 31, 2022
Bermuda Re Lloyd's Bank Credit Facility - Uncommitted [Member]
Line of Credit Facility [Line Items]
Capacity	$ 200,000,000
In Use	$ 85,000,000
Date of Expiry	Dec. 31, 2022
Bermuda Re Barclays Bilateral Letter of Credit Facility [Member]
Line of Credit Facility [Line Items]
Capacity	$ 200,000,000	200,000,000
In Use	$ 172,000,000	$ 186,000,000
Date of Expiry	Dec. 31, 2022	Dec. 31, 2022