Significant Accounting Policies (Schedule Of Property And Equipment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Gross Property and equipment	$ 556	$ 521
Less accumulated depreciation	(344)	(320)
Net property and equipment	212	201
Land [Member]
Property, Plant and Equipment [Line Items]
Gross Property and equipment	5	5
Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross Property and equipment	$ 54	47
Buildings And Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	10 years
Buildings And Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	40 years
Technology And Communications [Member]
Property, Plant and Equipment [Line Items]
Gross Property and equipment	$ 198	208
Technology And Communications [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Technology And Communications [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	7 years
Machinery, Production Equipment And Vehicles [Member]
Property, Plant and Equipment [Line Items]
Gross Property and equipment	$ 271	242
Machinery, Production Equipment And Vehicles [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Machinery, Production Equipment And Vehicles [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	9 years
Office Equipment, Furniture And Fixtures [Member]
Property, Plant and Equipment [Line Items]
Gross Property and equipment	$ 28	$ 19
Office Equipment, Furniture And Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Office Equipment, Furniture And Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	7 years