Claim and Claim Adjustment Expense Reserves and Future Policy Benefit Reserves (International - Excluding Hardy - Net Cumulative Paid Claim and Claim Adjustment Expenses) (Details) - USD ($) $ in Millions	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, 2014	Dec. 31, 2013
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	$ 19,908	$ 19,205	$ 18,701	$ 17,885
International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	2,003	1,940
Excluding Hardy | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	1,961
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented	1,348
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2013	56
Liability for unallocated claim adjustment expenses for accident years presented	37
Total net liability for unpaid claim and claim adjustment expenses	1,441
Excluding Hardy | 2013 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	212	209	203	192	$ 174	$ 165	$ 151	$ 135	$ 109	$ 48
Excluding Hardy | 2014 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	241	234	230	198	178	162	145	118	$ 50
Excluding Hardy | 2015 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	230	223	213	199	177	158	128	$ 55
Excluding Hardy | 2016 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	220	208	187	175	153	127	$ 64
Excluding Hardy | 2017 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	256	230	209	181	142	$ 63
Excluding Hardy | 2018 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	260	236	208	162	$ 88
Excluding Hardy | 2019 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	218	195	159	$ 71
Excluding Hardy | 2020 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	158	125	$ 58
Excluding Hardy | 2021 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	121	$ 54
Excluding Hardy | 2022 | International
Short-Duration Insurance Contracts, Net Cumulative Paid Claim and Claim Adjustment Expenses [Line Items]
Cumulative paid claims and allocated claim adjustment expense, net	$ 45