Reserves for Insurance Losses and Loss Adjustment Expenses (Short-duration Insurance Contracts, Claims Development) (Details) $ in Millions	Dec. 31, 2022 USD ($) claim	Dec. 31, 2021 USD ($)	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 ($)	Dec. 31, 2013 USD ($)
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	$ 3,083
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	3,049
All outstanding liabilities for loss and allocated loss adjustment expenses before 2013, net of reinsurance	10
Reserves for insurance losses and allocated loss adjustment expenses, net of reinsurance	44	$ 39	$ 37
2013
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	368	368	368	$ 368	$ 368	$ 369	$ 370	$ 370	$ 365	$ 376
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	672,284,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 368	368	368	368	368	368	368	366	364	$ 347
2014
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	388	388	388	388	388	388	388	389	390
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	525,298,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 388	388	388	388	388	388	388	388	$ 369
2015
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	272	272	272	272	272	272	271	274
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	342,280,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 272	272	272	272	272	272	272	$ 252
2016
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	328	328	328	328	328	327	326
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	476,056,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 328	328	328	328	328	327	$ 302
2017
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	315	315	315	315	314	310
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	481,750,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 315	315	315	315	315	$ 289
2018
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	273	273	272	272	271
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	506,449,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 273	273	273	273	$ 245
2019
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	305	305	306	303
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	542,314,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 305	305	306	$ 278
2020
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	339	339	343
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	494,382,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 339	339	$ 313
2021
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	237	243
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1
Cumulative number of reported claims | claim	493,222,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 236	$ 213
2022
Claims Development [Line Items]
Incurred claims and allocated loss adjustment expenses, net of reinsurance	258
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 28
Cumulative number of reported claims | claim	483,742,000,000
Cumulative paid claims and allocated loss adjustment expenses, net of reinsurance	$ 225