Employee Benefit Plans (Pension And Other Postretirement Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined benefit pension plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 2,271	$ 2,991
Expected return on plan assets	(3,081)	(4,497)
Net benefit credit	(810)	(1,506)
Other postretirement benefits plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	140	170
Interest cost	918	1,058
Net benefit credit	$ 1,058	$ 1,228