Pension Plan And Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 5
Company's expected additional annual contribution	$ 9
Common Stock in Treasury, Shares	31,269		31,269
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (gain)	$ 3	$ 4
Benefit obligation	34		$ 36
Discount rate		4.60%		4.20%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (gain)	1	$ 1
Benefit obligation	$ 13		$ 13
Discount rate		4.60%		4.20%
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	11,686		31,269