Pension And Other Postretirement Benefits (Net Periodic Benefit Cost) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 863	$ 640	$ 3,359	$ 3,442
Interest cost	1,771	1,613	5,159	4,791
Expected return on plan assets	(2,072)	(2,445)	(7,198)	(7,319)
Amortization of prior service cost	6	6	18	18
Amortization of transition obligation (asset)	0	0	0	0
Amortization of net actuarial loss	58	757	2,098	1,947
Net periodic benefit cost	626	571	3,436	2,879
Estimated contributions, next fiscal year					191
Contributions			143
Estimated contributions, current fiscal year	48		48
Supplemental Executive Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	18	18	80	84
Interest cost	77	67	219	213
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	29	30	87	88
Amortization of transition obligation (asset)	0	0	0	0
Amortization of net actuarial loss	26	18	98	68
Net periodic benefit cost	150	133	484	453
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	194	137	582	519
Interest cost	185	186	555	572
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	16	16	48	48
Amortization of transition obligation (asset)	28	28	84	84
Amortization of net actuarial loss	0	0	0	0
Net periodic benefit cost	423	367	1,269	1,223
Estimated contributions, next fiscal year					690
Contributions			518
Estimated contributions, current fiscal year	$ 172		$ 172