Accumulated Other Comprehensive Income (Loss) (Amounts Reclassified Out Of Each Component Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on disposal of investment securities		$ 1,988	$ 2,041	$ 1,226
Interest income		95,313	93,774	91,594
Prior service credit		895	128	1,316
Net actuarial losses		(887)	(9,709)	11,860
Income before income taxes		38,876	38,980	37,907
Income tax (expense) benefit		(10,539)	(9,625)	(12,377)
Net income		28,337	29,355	25,530
Total reclassified for the period		833	1,420	(11)
Securities Available For Sale and Transferred Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassified for the period		1,383	1,497	784
Pension And Post-Retirement Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassified for the period		(550)	(77)	$ (795)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassified for the period		833	1,420
Reclassification out of Accumulated Other Comprehensive Income [Member] | Securities Available For Sale and Transferred Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on disposal of investment securities		1,988	2,041
Interest income		263	437
Income before income taxes		(2,251)	(2,478)
Income tax (expense) benefit		(868)	(981)
Net income		(1,383)	(1,497)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension And Post-Retirement Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credit	[1]	48	48
Net actuarial losses	[1]	(943)	(176)
Income before income taxes		895	128
Income tax (expense) benefit		345	51
Net income		$ 550	$ 77

[1] These items are included in the computation of net periodic pension expense. See Note 17 - Employee Benefit Plans for additional information.