Benefit Plans (Fair Value of Plan Assets Measured on a Recurring Basis) (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 2,577	$ 2,420	$ 2,285
Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,577	2,420
Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,719	1,664
Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	777	699
Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	934	956
Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	9
Fair Value Measured at Net Asset Value Per Share | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	838	756
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	20
Total fixed maturity securities trading | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	793	782
Total fixed maturity securities trading | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Total fixed maturity securities trading | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	785	773
Total fixed maturity securities trading | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	9
Corporate and other bonds | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	653	652
Corporate and other bonds | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate and other bonds | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	645	643
Corporate and other bonds | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	9
States, municipalities and political subdivisions | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30	32
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	30	32
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	110	98
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	110	98
Asset-backed | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity securities | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	873	803
Equity securities | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	732	666
Equity securities | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	141	137
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	45	58
Short term investments | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	45	20
Short term investments | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	38
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	8	8
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	8	8
Other assets | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash | Total | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	13
Cash | Level 1 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	13
Cash | Level 2 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash | Level 3 | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0