ACQUISITIONS AND FDIC INDEMNIFICATION ASSET: (Details Textual) - USD ($)	3 Months Ended								12 Months Ended			54 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2013	Aug. 16, 2013
Business Acquisition [Line Items]
Gain on Sale of certain assets and liabilities of Insurance Brokerage Operation									$ 0	$ 0	$ 0
Deposits	$ 3,275,357,000				$ 2,436,727,000				3,275,357,000	2,436,727,000
Goodwill	78,592,000				34,355,000				78,592,000	34,355,000
Reimbursements from the FDIC												$ (24,300,000)
Covered loans					3,200,000					3,200,000
Assets	4,023,250,000				3,008,718,000				4,023,250,000	3,008,718,000
Net Income (Loss) Attributable to Parent	$ 14,364,000	$ 12,257,000	$ 12,569,000	$ 9,682,000	$ 11,056,000	$ 11,313,000	$ 15,261,000	$ 8,953,000	48,872,000	$ 46,583,000	$ 29,131,000
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%