Pensions And Other Postretirement Benefits (Fair Value Of Plan Assets) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 2,373	$ 2,073
Fair Value Inputs Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,177	1,185
Fair Value Inputs Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,196	888
Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,154	1,142
Common Stock | Fair Value Inputs Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,154	1,142
Common Stock | Fair Value Inputs Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	562	481
Debt Securities | Fair Value Inputs Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Debt Securities | Fair Value Inputs Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	562	481
International equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	397	324
International equity securities | Fair Value Inputs Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International equity securities | Fair Value Inputs Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	397	324
Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	233	79
Commingled Funds | Fair Value Inputs Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Commingled Funds | Fair Value Inputs Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	233	79
Interest bearing cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23	43
Interest bearing cash | Fair Value Inputs Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23	43
Interest bearing cash | Fair Value Inputs Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. government and agencies securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	4
U.S. government and agencies securities | Fair Value Inputs Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. government and agencies securities | Fair Value Inputs Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 4	$ 4