Claim and Claim Adjustment Expense Reserves (International - Hardy - Net Incurred Claims and Allocated Claim Adjustment Expenses) (Details) - International $ in Millions	Dec. 31, 2023 USD ($) claim	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Hardy
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 2,082
IBNR	420
Hardy | 2014
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	167	$ 166	$ 167	$ 169	$ 170	$ 170	$ 169	$ 175	$ 182	$ 183
IBNR	$ (1)
Cumulative Number of Claims | claim	8,534,000,000
Hardy | 2015
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 177	178	176	175	173	175	175	177	187
IBNR	$ (3)
Cumulative Number of Claims | claim	9,741,000,000
Hardy | 2016
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 223	219	218	224	223	233	244	227
IBNR	$ 6
Cumulative Number of Claims | claim	10,895,000,000
Hardy | 2017
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 239	251	251	243	242	252	243
IBNR	$ (5)
Cumulative Number of Claims | claim	13,294,000,000
Hardy | 2018
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 324	307	307	302	298	268
IBNR	$ 36
Cumulative Number of Claims | claim	15,366,000,000
Hardy | 2019
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 220	224	217	223	219
IBNR	$ 25
Cumulative Number of Claims | claim	11,670,000,000
Hardy | 2020
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 192	195	201	210
IBNR	$ 55
Cumulative Number of Claims | claim	7,036,000,000
Hardy | 2021
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 154	168	177
IBNR	$ 59
Cumulative Number of Claims | claim	3,831,000,000
Hardy | 2022
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 186	190
IBNR	$ 96
Cumulative Number of Claims | claim	2,371,000,000
Hardy | 2023
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 200
IBNR	$ 152
Cumulative Number of Claims | claim	1,388,000,000
Excluding Hardy
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 3,682
IBNR	1,073
Excluding Hardy | 2014
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	288	286	283	290	289	272	279	291	291	$ 276
IBNR	$ 15
Cumulative Number of Claims | claim	25,130
Excluding Hardy | 2015
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 281	285	285	283	280	286	303	304	$ 289
IBNR	$ 19
Cumulative Number of Claims | claim	23,608
Excluding Hardy | 2016
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 309	292	290	276	285	288	302	$ 284
IBNR	$ 36
Cumulative Number of Claims | claim	18,079
Excluding Hardy | 2017
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 393	360	371	376	383	363	$ 299
IBNR	$ 39
Cumulative Number of Claims | claim	18,841
Excluding Hardy | 2018
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 411	401	388	389	385	$ 367
IBNR	$ 48
Cumulative Number of Claims | claim	21,327
Excluding Hardy | 2019
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 362	360	352	355	$ 342
IBNR	$ 61
Cumulative Number of Claims | claim	18,993
Excluding Hardy | 2020
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 347	362	372	$ 381
IBNR	$ 107
Cumulative Number of Claims | claim	15,744
Excluding Hardy | 2021
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 375	397	$ 408
IBNR	$ 162
Cumulative Number of Claims | claim	15,136
Excluding Hardy | 2022
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 438	$ 428
IBNR	$ 227
Cumulative Number of Claims | claim	11,899
Excluding Hardy | 2023
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 478
IBNR	$ 359
Cumulative Number of Claims | claim	7,869