Employee Retirement Plans (Domestic Defined Benefit Plan Assets) (Details) - Pension Benefits [Member] - United States [Member] - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Equity Securities [Member] | U.S. Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 494	$ 363
Equity Securities [Member] | U.S. Companies [Member] | Quoted Market Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2	2
Equity Securities [Member] | U.S. Companies [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		492	361
Equity Securities [Member] | International Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		387	324
Equity Securities [Member] | International Companies [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		387	324
Fixed Income Securities [Member] | U.S. Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2,017	1,626
Fixed Income Securities [Member] | U.S. Companies [Member] | Quoted Market Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		226	183
Fixed Income Securities [Member] | U.S. Companies [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,791	1,443
Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	64	82
Private Equity Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	64	82
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	145	148
Real Estate [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	145	148
Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		46	199
Cash Equivalents [Member] | Quoted Market Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		46	199
Defined Benefit Plans Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		3,153	2,742
Defined Benefit Plans Assets [Member] | Quoted Market Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		274	384
Defined Benefit Plans Assets [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2,670	2,128
Defined Benefit Plans Assets [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 209	$ 230

[1] This category includes venture capital, leverage buyouts and distressed debt limited partnerships invested primarily in U.S. companies. The inputs are valued by discounted cash flow analysis and comparable sale analysis.

[2] This category includes industrial, office, apartments, hotels, infrastructure and retail investments which are limited partnerships predominately in the U.S. The inputs are valued by discounted cash flow analysis; comparable sale analysis and periodic external appraisals.