Claim and Claim Adjustment Expense Reserves (International - Excluding Hardy - Net Strengthening or Releasing of Prior Accident Year Reserves) (Details) - Excluding Hardy - International - USD ($) $ in Millions	12 Months Ended									24 Months Ended	36 Months Ended	48 Months Ended	60 Months Ended	72 Months Ended	84 Months Ended	96 Months Ended	108 Months Ended	120 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2023
2014
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	$ 2	$ 3	$ (7)	$ 1	$ 17	$ (7)	$ (12)	$ 0	$ 15									$ 12
2015
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	(4)	0	2	3	(6)	(17)	(1)	$ 15									$ (8)
2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	17	2	14	(9)	(3)	(14)	$ 18									$ 25
2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	33	(11)	(5)	(7)	20	$ 64									$ 94
2018
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	10	13	(1)	4	$ 18									$ 44
2019
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	2	8	(3)	$ 13									$ 20
2020
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	(15)	(10)	$ (9)									$ (34)
2021
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	(22)	$ (11)									$ (33)
2022
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Number of Claims	$ 10									$ 10