Benefit Plans (Fair Value of Plan Assets Measured on a Recurring Basis) (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,984	$ 2,025	$ 2,577
Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,984	2,025
Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,584	1,470
Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	225	363
Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,345	1,091
Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14	16
Fair Value Measured at Net Asset Value Per Share | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	375	534
Fair Value Measured at Net Asset Value Per Share | Fair Value, Recurring | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25	21
Total fixed maturity securities | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,348	1,081
Total fixed maturity securities | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	0
Total fixed maturity securities | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,324	1,065
Total fixed maturity securities | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14	16
Corporate and other bonds | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,057	866
Corporate and other bonds | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	0
Corporate and other bonds | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,041	859
Corporate and other bonds | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	7
States, municipalities and political subdivisions | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50	49
States, municipalities and political subdivisions | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
States, municipalities and political subdivisions | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50	49
States, municipalities and political subdivisions | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Asset-backed | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	241	166
Asset-backed | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Asset-backed | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	233	157
Asset-backed | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	9
Equity securities | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	125	231
Equity securities | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	119	218
Equity securities | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	13
Equity securities | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Short-term investments | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	96	146
Short-term investments | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	96	145
Short-term investments | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1
Short-term investments | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other assets | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	12
Other assets | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other assets | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	12
Other assets | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0