Claim, Claim Adjustment Expense and Future Policy Benefit Reserves (International - Excluding Hardy - Net Incurred Claims and Allocated Claim Adjustment Expenses) (Details) - Excluding Hardy - International $ in Millions	Dec. 31, 2021 USD ($) claim	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 3,371
IBNR	845
2012
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	250	$ 236	$ 241	$ 247	$ 254	$ 261	$ 262	$ 269	$ 285	$ 278
IBNR	$ 16
Cumulative Number of Claims | claim	24,998
2013
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 251	247	251	260	269	273	293	301	$ 285
IBNR	$ 12
Cumulative Number of Claims | claim	23,967
2014
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 294	301	300	283	291	303	303	$ 288
IBNR	$ 16
Cumulative Number of Claims | claim	24,946
2015
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 297	294	292	298	316	317	$ 301
IBNR	$ 27
Cumulative Number of Claims | claim	23,357
2016
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 302	287	297	300	315	$ 296
IBNR	$ 37
Cumulative Number of Claims | claim	17,776
2017
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 388	393	401	378	$ 312
IBNR	$ 84
Cumulative Number of Claims | claim	18,470
2018
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 406	407	402	$ 384
IBNR	$ 81
Cumulative Number of Claims | claim	20,726
2019
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 368	371	$ 357
IBNR	$ 91
Cumulative Number of Claims | claim	17,974
2020
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 389	$ 398
IBNR	$ 184
Cumulative Number of Claims | claim	13,909
2021
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Incurred claims and allocated claim adjustment expense, net	$ 426
IBNR	$ 297
Cumulative Number of Claims | claim	10,401