Pension and Other Postretirement Employee Benefits (Components Of Net Periodic Cost (Benefit)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,862	$ 1,507
Interest cost	4,081	4,252
Expected return on plan assets	(4,603)	(4,766)
Amortization of prior service cost (credit)	72	130
Amortization of actuarial loss	3,856	3,917
Net periodic cost (benefit)	5,268	5,040
Other Postretirement Employee Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	5
Interest cost	321	355
Amortization of prior service cost (credit)	(2,219)	(2,220)
Amortization of actuarial loss	398	428
Net periodic cost (benefit)	$ (1,497)	$ (1,432)