ACQUISITIONS AND FDIC INDEMNIFICATION ASSET: (Details Textual) - USD ($)	3 Months Ended								12 Months Ended			54 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Aug. 16, 2013
Business Acquisition [Line Items]
Deposits	$ 2,442,369,000				$ 2,457,197,000				$ 2,442,369,000	$ 2,457,197,000
Goodwill	39,489,000				39,489,000				39,489,000	39,489,000
Reimbursements from the FDIC												$ (24,300,000)
Covered loans	6,500,000				7,300,000				6,500,000	7,300,000
Assets	2,979,585,000				3,002,485,000				2,979,585,000	3,002,485,000
Net Income (Loss) Attributable to Parent	7,114,000	$ 8,398,000	$ 6,923,000	$ 7,761,000	$ 9,181,000	$ 8,272,000	$ 8,488,000	$ 7,831,000	30,196,000	33,772,000	$ 31,534,000
Bank of America
Business Acquisition [Line Items]
Goodwill recorded, which is expected to be tax deductable													$ 1,900
First National Bank Of Danville
Business Acquisition [Line Items]
Losses on assets, threshold under loss-sharing agreement (up to $29 million)									$ 29,000,000
Percentage of losses to be reimbursed by the FDIC, on losses up to the threshold amount (percent)									80.00%
Percentage of losses to be reimbursed by the FDIC, on losses exceeding the threshold amount (percent)									95.00%
Forrest Sherer [Member]
Business Acquisition [Line Items]
Revenues									$ 7,600,000	8,300,000	8,200,000
Assets	13,000,000								13,000,000
Common equity capital	$ 10,000,000								10,000,000
Net Income (Loss) Attributable to Parent									$ 168,000	$ 554,000	$ 592,000