MERGERS AND ACQUISITIONS - Pro forma results of operations of Riverside Bank since acquisition date (Details) (Pro forma results of operations of Riverside Bank since acquisition date, USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pro forma results of operations of Riverside Bank since acquisition date
Total revenue	$ 39,841	$ 39,640	$ 43,001
Net income	6,411	7,136	7,654
Net income available to common shareholders	$ 6,245	$ 6,975	$ 7,438
Earnings per share
Basic	$ 2.26	$ 2.59	$ 2.77
Diluted	$ 2.24	$ 2.57	$ 2.64