Disclosures about fair value of assets and liabilities (Details Textual) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Disclosures About Fair Value of Assets and Liabilities (Textual) [Abstract]
Fair value adjustments on impaired loans	$ 2,400,000	$ 1,900,000
Increase in carrying amount of mortgage servicing rights	$ 135,000	$ 64,000