Employee Benefit Plans (Estimated Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 8,294	$ 10,971	$ 11,256
Pension Benefits | Fixed maturity securities AFS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,802	9,065
Pension Benefits | Corporate fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,001	4,305
Pension Benefits | U.S. government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,507	1,904
Pension Benefits | Foreign government
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	769	1,116
Pension Benefits | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	277	83
Pension Benefits | Municipals
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	159	248
Pension Benefits | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	396	626
Pension Benefits | Other (1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	693	783
Pension Benefits | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	570	895
Pension Benefits | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	896	997
Pension Benefits | Derivative assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26	14
Pension Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,130	2,778
Pension Benefits | Level 1 | Fixed maturity securities AFS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,653	2,121
Pension Benefits | Level 1 | Corporate fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Level 1 | U.S. government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,462	1,824
Pension Benefits | Level 1 | Foreign government
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Level 1 | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	87	0
Pension Benefits | Level 1 | Municipals
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Level 1 | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12	142
Pension Benefits | Level 1 | Other (1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	92	155
Pension Benefits | Level 1 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	416	601
Pension Benefits | Level 1 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40	42
Pension Benefits | Level 1 | Derivative assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	14
Pension Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,244	7,226
Pension Benefits | Level 2 | Fixed maturity securities AFS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,091	6,942
Pension Benefits | Level 2 | Corporate fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,946	4,305
Pension Benefits | Level 2 | U.S. government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	45	80
Pension Benefits | Level 2 | Foreign government
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	769	1,115
Pension Benefits | Level 2 | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	190	83
Pension Benefits | Level 2 | Municipals
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	159	248
Pension Benefits | Level 2 | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	384	484
Pension Benefits | Level 2 | Other (1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	598	627
Pension Benefits | Level 2 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	151	283
Pension Benefits | Level 2 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
Pension Benefits | Level 2 | Derivative assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	0
Pension Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	920	967
Pension Benefits | Level 3 | Fixed maturity securities AFS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	58	2
Pension Benefits | Level 3 | Corporate fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55	0	0
Pension Benefits | Level 3 | U.S. government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Level 3 | Foreign government
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1	0
Pension Benefits | Level 3 | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Level 3 | Municipals
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Level 3 | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Level 3 | Other (1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	1	0
Pension Benefits | Level 3 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	11	0
Pension Benefits | Level 3 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	855	954
Pension Benefits | Level 3 | Derivative assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	0
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,303	1,443	$ 1,492
Other Postretirement Benefits | Fixed maturity securities AFS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,256	1,387
Other Postretirement Benefits | Corporate fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	205	222
Other Postretirement Benefits | U.S. government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	68	69
Other Postretirement Benefits | Foreign government
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61	51
Other Postretirement Benefits | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	10
Other Postretirement Benefits | Municipals
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	8
Other Postretirement Benefits | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	859	968
Other Postretirement Benefits | Other (1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44	59
Other Postretirement Benefits | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47	55
Other Postretirement Benefits | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1
Other Postretirement Benefits | Derivative assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	589	625
Other Postretirement Benefits | Level 1 | Fixed maturity securities AFS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	542	569
Other Postretirement Benefits | Level 1 | Corporate fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 1 | U.S. government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	68	69
Other Postretirement Benefits | Level 1 | Foreign government
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 1 | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	0
Other Postretirement Benefits | Level 1 | Municipals
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 1 | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	463	486
Other Postretirement Benefits | Level 1 | Other (1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	14
Other Postretirement Benefits | Level 1 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47	55
Other Postretirement Benefits | Level 1 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1
Other Postretirement Benefits | Level 1 | Derivative assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	714	818
Other Postretirement Benefits | Level 2 | Fixed maturity securities AFS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	714	818
Other Postretirement Benefits | Level 2 | Corporate fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	205	222
Other Postretirement Benefits | Level 2 | U.S. government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 2 | Foreign government
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61	51
Other Postretirement Benefits | Level 2 | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	10
Other Postretirement Benefits | Level 2 | Municipals
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	8
Other Postretirement Benefits | Level 2 | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	396	482
Other Postretirement Benefits | Level 2 | Other (1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36	45
Other Postretirement Benefits | Level 2 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 2 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 2 | Derivative assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Fixed maturity securities AFS
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Corporate fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | U.S. government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Foreign government
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Municipals
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Other (1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3 | Derivative assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0