Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	$ 4,721	$ 5,028
Before reclassifications	(334)	(498)
Reclassifications	(387)	(251)
Balance at end of period	4,000	4,279
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net gain on sales of securities	587	380
Reclassification adjustment, net of taxes	(387)	(251)
Unrealized gains and losses on available-for-sale securities [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	4,875	5,180
Before reclassifications	(342)	(505)
Reclassifications	(387)	(251)
Balance at end of period	4,146	4,424
Unrealized gains and losses on available-for-sale securities [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net gain on sales of securities	587	380
Provision for income taxes	200	129
Reclassification adjustment, net of taxes	387	251
Changes in pension plan assets and benefit obligations [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(154)	(152)
Before reclassifications	8	7
Reclassifications	0	0
Balance at end of period	$ (146)	$ (145)