Retirement Plans (Schedule Of Components Of Periodic Benefit Costs For Defined-Benefit Pension, Postretirement Healthcare And Supplemental Retirement Plan) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Defined-Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 215	$ 194
Interest cost	476	455
Expected return on plan assets	(509)	(513)
Amortization of net loss	473	342
Net periodic benefit cost	655	478
Postretirement Healthcare Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	8	10
Interest cost	18	20
Expected return on plan assets
Amortization of net loss	6	7
Net periodic benefit cost	32	37
Supplemental Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	5
Interest cost	40	40
Expected return on plan assets
Amortization of net loss	48	38
Net periodic benefit cost	$ 95	$ 83