Premises and Equipment - Premises and equipment - (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Total cost	$ 17,641	$ 14,175
Accumulated depreciation and amortization	(6,736)	(6,084)
Net	10,905	8,091
Land
Property, Plant and Equipment [Line Items]
Total cost	2,659	1,919
Buildings
Property, Plant and Equipment [Line Items]
Total cost	8,819	6,752
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total cost	715	715
Equipment
Property, Plant and Equipment [Line Items]
Total cost	5,396	4,777
Construction in progress
Property, Plant and Equipment [Line Items]
Total cost	$ 52	$ 12