SELECTED QUARTERLY DATA (UNAUDITED): (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Selected Quarterly Financial Information [Abstract]
After Tax Gain on Sale of certain assets and liabilities of Insurance Brokerage Operation				$ 5,750
Gain on Sale of certain assets and liabilities of Insurance Brokerage Operation		$ (199)							$ 12,800	$ 0	$ 12,822	$ 0
Interest Income	$ 29,416	28,805	$ 28,128	27,846	$ 27,579	$ 27,450	$ 27,150	$ 27,201
Interest Expense	1,734	1,697	1,568	1,339	1,173	1,099	1,091	1,044		6,338	4,407	4,169
NET INTEREST INCOME	27,682	27,108	26,560	26,507	26,406	26,351	26,059	26,157		107,857	104,973	104,507
Provision For Loan Losses	1,474	1,185	1,040	1,596	939	1,091	435	835		5,295	3,300	4,700
Net income	$ 2,616	$ 8,794	$ 8,352	$ 9,369	$ 8,344	$ 8,162	$ 8,232	$ 13,675		$ 29,131	$ 38,413	$ 30,196
Net Income Per Share (in dollars per share)	$ 0.21	$ 0.72	$ 0.68	$ 0.77	$ 0.69	$ 0.67	$ 0.68	$ 1.08		$ 2.38	$ 3.12	$ 2.35