Benefit Plans (Fair Values of Pension and Postretirement Plan Assets) (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 8,793,000,000	$ 8,911,000,000	$ 8,167,000,000
Pension [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	1,147,000,000	950,000,000
Pension [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	60,000,000	64,000,000
Pension [Member] | Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	88,000,000	90,000,000
Pension [Member] | Corporate Debt Security, Above Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	3,442,000,000	3,760,000,000
Pension [Member] | Corporate Debt Security, Below Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	1,032,000,000	868,000,000
Pension [Member] | Common stock: International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	373,000,000	316,000,000
Pension [Member] | Common stock: U.S. equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	856,000,000	970,000,000
Pension [Member] | Other, Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	289,000,000	377,000,000
Pension [Member] | U S Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 873,000,000	$ 924,000,000
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List]	NAV [Member]	NAV [Member]
Pension [Member] | U S Small Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 462,000,000	$ 455,000,000
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List]	NAV [Member]	NAV [Member]
Pension [Member] | International Developed Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 125,000,000	$ 114,000,000
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List]	NAV [Member]	NAV [Member]
Pension [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 46,000,000	$ 23,000,000
Pension [Member] | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	7,287,000,000	7,395,000,000
Pension [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	1,281,000,000	1,307,000,000
Pension [Member] | Level 1 [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Pension [Member] | Level 1 [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Pension [Member] | Level 1 [Member] | Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Pension [Member] | Level 1 [Member] | Corporate Debt Security, Above Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Pension [Member] | Level 1 [Member] | Corporate Debt Security, Below Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Pension [Member] | Level 1 [Member] | Common stock: International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	373,000,000	316,000,000
Pension [Member] | Level 1 [Member] | Common stock: U.S. equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	856,000,000	970,000,000
Pension [Member] | Level 1 [Member] | Other, Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	52,000,000	21,000,000
Pension [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	6,006,000,000	6,088,000,000
Pension [Member] | Level 2 [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	1,147,000,000	950,000,000
Pension [Member] | Level 2 [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	60,000,000	64,000,000
Pension [Member] | Level 2 [Member] | Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	88,000,000	90,000,000
Pension [Member] | Level 2 [Member] | Corporate Debt Security, Above Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	3,442,000,000	3,760,000,000
Pension [Member] | Level 2 [Member] | Corporate Debt Security, Below Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	1,032,000,000	868,000,000
Pension [Member] | Level 2 [Member] | Common stock: International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Pension [Member] | Level 2 [Member] | Common stock: U.S. equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Pension [Member] | Level 2 [Member] | Other, Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	237,000,000	356,000,000
Pension [Member] | NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	1,460,000,000	1,493,000,000
Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	185,000,000	201,000,000	$ 213,000,000
Postretirement Benefit Plan [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	5,000,000	6,000,000
Postretirement Benefit Plan [Member] | Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	3,000,000	4,000,000
Postretirement Benefit Plan [Member] | Corporate Debt Security, Above Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	55,000,000	55,000,000
Postretirement Benefit Plan [Member] | Corporate Debt Security, Below Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	10,000,000	11,000,000
Postretirement Benefit Plan [Member] | Other, Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	7,000,000
Postretirement Benefit Plan [Member] | U S Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 84,000,000	$ 97,000,000
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List]	NAV [Member]	NAV [Member]
Postretirement Benefit Plan [Member] | International Developed Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 25,000,000	$ 25,000,000
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List]	NAV [Member]	NAV [Member]
Postretirement Benefit Plan [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 3,000,000	$ (4,000,000)
Postretirement Benefit Plan [Member] | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	73,000,000	83,000,000
Postretirement Benefit Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Postretirement Benefit Plan [Member] | Level 1 [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Postretirement Benefit Plan [Member] | Level 1 [Member] | Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Postretirement Benefit Plan [Member] | Level 1 [Member] | Corporate Debt Security, Above Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Postretirement Benefit Plan [Member] | Level 1 [Member] | Corporate Debt Security, Below Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Postretirement Benefit Plan [Member] | Level 1 [Member] | Other, Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Postretirement Benefit Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	73,000,000	83,000,000
Postretirement Benefit Plan [Member] | Level 2 [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	5,000,000	6,000,000
Postretirement Benefit Plan [Member] | Level 2 [Member] | Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	3,000,000	4,000,000
Postretirement Benefit Plan [Member] | Level 2 [Member] | Corporate Debt Security, Above Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	55,000,000	55,000,000
Postretirement Benefit Plan [Member] | Level 2 [Member] | Corporate Debt Security, Below Investment Grade [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	10,000,000	11,000,000
Postretirement Benefit Plan [Member] | Level 2 [Member] | Other, Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	7,000,000
Postretirement Benefit Plan [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	0	0
Postretirement Benefit Plan [Member] | NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, net	$ 109,000,000	$ 122,000,000