Employee Benefits (Schedule Of Net Benefit Costs And Amounts Recognized In Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 930	$ 938	$ 842
Interest cost	2,723	2,751	2,465
Expected return on plan assets	(2,279)	(1,935)	(1,652)
Net amortization	1,567	1,899	1,646
Net periodic benefit cost	2,941	3,653	3,301
Net loss (gain) emerging	5,804	(1,521)	3,804
Prior service cost			1,484
Amortization of net loss	(1,271)	(1,602)	(1,381)
Amortization of prior service cost	(296)	(297)	(265)
Total recognized in OCI	4,237	(3,420)	3,642
Total net periodic benefit cost and OCI	7,178	233	6,943
Post-Retirement Healthcare Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	16	45	85
Interest cost	840	919	1,067
Net amortization	418	377	427
Net periodic benefit cost	1,274	1,341	1,579
Net loss (gain) emerging	816	(656)	1,039
Amortization of net loss	(118)	(51)	(101)
Amortization of transition obligation	(114)	(114)	(114)
Amortization of prior service cost	(186)	(212)	(212)
Total recognized in OCI	398	(1,033)	612
Total net periodic benefit cost and OCI	$ 1,672	$ 308	$ 2,191