Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Balance	$ 2,215	$ 3,102
Net current period change, Pension and postretirement benefit plans	(448)	(396)	172
Net current period change, Interest rate swaps	226	(123)	(366)
Reclassification adjustments for (gains) losses reclassified into income	(329)	(646)	(1,354)
Unrealized (Gains)/ Losses on Securities [Member]
Balance	6,033	6,612	4,675	5,763
Net current period change, Unrealized (gains) losses on securities	(250)	2,583	266
Reclassification adjustments for (gains) losses reclassified into income	(329)	(646)	(1,354)
Pension and Postretirement Benefit Plans [Member]
Balance	(3,130)	(2,682)	(2,286)	(2,458)
Net current period change, Pension and postretirement benefit plans	(448)	(396)	172
Reclassification adjustments for (gains) losses reclassified into income	0	0	0
Interest Rate Swap Agreements [Member]
Balance	(688)	(914)	(791)	(425)
Net current period change, Interest rate swaps	226	(123)	(366)
Reclassification adjustments for (gains) losses reclassified into income	0	0	0
Unrealized Gains (Losses) on Securities Deemed Other than Temporarily Impaired [Member]
Balance	0	86	79	(213)
Net current period change, Unrealized gains (losses) on securities deemed other than temporarily impaired	(86)	7	292
Reclassification adjustments for (gains) losses reclassified into income	0	0	0
Accumulated Other Comprehensive Income (Loss) [Member]
Balance	2,215	3,102	1,677	2,667
Net current periodic change, Accumulated other comprehensive income (loss)	(558)	2,071	364
Reclassification adjustments for (gains) losses reclassified into income	$ (329)	$ (646)	$ (1,354)