Retirement Plans (Components Of Net Periodic Benefits Cost) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Pension Benefits [Member]
Service cost	$ 1,172	$ 875	$ 2,344	$ 1,750
Interest cost	1,363	1,308	2,726	2,617
Expected return on plan assets	(1,373)	(1,161)	(2,745)	(2,323)
Amortization of net loss	586	570	1,172	1,140
Net periodic benefit cost	1,748	1,592	3,497	3,184
Other Post-Retirement Benefits [Member]
Service cost	35	31	69	62
Interest cost	152	139	305	278
Amortization of prior service cost	(13)	(13)	(27)	(26)
Amortization of net loss	134	76	269	151
Amortization of transition obligation	2	1	3	2
Net periodic benefit cost	$ 310	$ 234	$ 619	$ 467