Accumulated Other Comprehensive (Loss) Income - Components of Accumulated Other Comprehensive (Loss) Income, Net of Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Accumulated other comprehensive (loss) income
Net Unrealized Gains on Available for Sale Investment Securities, Beginning Balance	$ 8,344		$ 7,306
Net Change in Fair Value of Derivative Used for Cash Flow Hedges, Beginning Balance	(1,241)		(932)
Net Change Related to Defined Benefit Pension Plan, Beginning Balance	(14,023)		(12,475)
Accumulated Other Comprehensive (Loss) Income, Beginning Balance	(6,920)	[1]	(6,101)
Net Unrealized Gains on Available for Sale Investment Securities, Net Change	(1,033)		(751)
Net Change in Fair Value of Derivative Used for Cash Flow Hedges, Net Change	105		113
Net Change Related to Defined Benefit Pension Plan, Net Change	149		152
Accumulated Other Comprehensive (loss) Income, Net Change	(779)		(486)
Net Unrealized Gains on Available for Sale Investment Securities, Ending Balance	7,311		6,555
Net Change in fair Value of Derivative Used for Cash Flow Hedges, Ending Balance	(1,136)		(819)
Net Change Related to Defined Benefit Pension Plan, Ending Balance	(13,874)		(12,323)
Accumulated Other Comprehensive (Loss) Income, Ending Balance	$ (7,699)		$ (6,587)

[1] Note: The consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U. S. generally accepted accounting principles for complete financial statements. See accompanying notes to the unaudited consolidated financial statements.