FAIR VALUES OF FINANCIAL INSTRUMENTS: (Details 4) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Carrying amount and estimated fair value of financial instruments
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held	$ 2,974	$ 2,974	$ 7,132	$ 13,974
Securities available-for-sale	926,717	784,916
Restricted stock	15,394	10,390
Accrued interest receivable	18,523	13,970
Deposits	(3,275,357)	(2,436,727)
Level 1
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	26,275	23,418
Securities available-for-sale		0
Level 2
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	101,151	50,970
Securities available-for-sale	920,533	778,523
Accrued interest receivable	3,583	3,005
Deposits	(3,278,099)	(2,426,128)
Short-term borrowings	(80,119)	(69,656)
Accrued interest payable	(1,739)	(609)
Level 3
Carrying amount and estimated fair value of financial instruments
Securities available-for-sale	6,184	6,393
Loans, net	2,648,692	1,889,795
Accrued interest receivable	14,940	10,965
Reported Value Measurement [Member]
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	127,426	74,388
Securities available-for-sale	926,717	784,916
Restricted stock	15,394	10,390
Loans, net	2,636,447	1,933,552
Accrued interest receivable	18,523	13,970
Deposits	(3,275,357)	(2,436,727)
Short-term borrowings	(80,119)	(69,656)
Accrued interest payable	(1,739)	(609)
Estimate of Fair Value Measurement [Member]
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	127,426	74,388
Securities available-for-sale	926,717	784,916
Loans, net	2,648,692	1,889,795
Accrued interest receivable	18,523	13,970
Deposits	(3,278,099)	(2,426,128)
Short-term borrowings	(80,119)	(69,656)
Accrued interest payable	$ (1,739)	$ (609)

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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Amount of interest payable on debt, including, but not limited to, trade payables.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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The cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity).

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Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

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