Pension Plan And Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 4	$ 4
Employer contributions	3
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 1	$ 1
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Common stock purchased under the terms of the Non-Qualified Plan presented as treasury stock	31,269		47,149