FAIR VALUE MEASUREMENT AND DISCLOSURE (Schedule of Carrying Amounts and Estimated Fair Value for Financial Instrument Assets and Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial assets:
Available-for-sale Securities	$ 796,687	$ 789,899
Held-to-maturity securities, at amortized cost	93,192	94,073
Held-to-maturity Securities, Fair Value	91,874	94,913
Mortgage servicing rights	1,840	1,766
Financial liabilities:
Time deposits	532,244	512,483
Short-term Debt, Fair Value	552,289	541,605
Long-term Debt, Fair Value	10,658	10,777
Subordinated debentures	45,588	44,333
Residential Real Estate
Financial assets:
Loans receivable, net of allowance	842,132	853,056
Commercial Real Estate
Financial assets:
Loans receivable, net of allowance	1,119,406	1,115,618
Commercial
Financial assets:
Loans receivable, net of allowance	404,925	401,902
Home Equity
Financial assets:
Loans receivable, net of allowance	311,142	318,230
Consumer
Financial assets:
Loans receivable, net of allowance	16,880	17,335
Readily Available Market Prices (Level 1)
Financial assets:
Held-to-maturity Securities, Fair Value	0	0
Mortgage servicing rights	0	0
Financial liabilities:
Time deposits	0	0
Short-term Debt, Fair Value	0	0
Long-term Debt, Fair Value	0	0
Subordinated debentures	0	0
Readily Available Market Prices (Level 1) \| Residential Real Estate
Financial assets:
Loans receivable, net of allowance	0	0
Readily Available Market Prices (Level 1) \| Commercial Real Estate
Financial assets:
Loans receivable, net of allowance	0	0
Readily Available Market Prices (Level 1) \| Commercial
Financial assets:
Loans receivable, net of allowance	0	0
Readily Available Market Prices (Level 1) \| Home Equity
Financial assets:
Loans receivable, net of allowance	0	0
Readily Available Market Prices (Level 1) \| Consumer
Financial assets:
Loans receivable, net of allowance	0	0
Observable Market Data (Level 2)
Financial assets:
Held-to-maturity Securities, Fair Value	91,874	94,913
Mortgage servicing rights	0	0
Financial liabilities:
Time deposits	532,244	512,483
Short-term Debt, Fair Value	552,289	541,605
Long-term Debt, Fair Value	10,658	10,777
Subordinated debentures	45,588	44,333
Observable Market Data (Level 2) \| Residential Real Estate
Financial assets:
Loans receivable, net of allowance	0	0
Observable Market Data (Level 2) \| Commercial Real Estate
Financial assets:
Loans receivable, net of allowance	0	0
Observable Market Data (Level 2) \| Commercial
Financial assets:
Loans receivable, net of allowance	0	0
Observable Market Data (Level 2) \| Home Equity
Financial assets:
Loans receivable, net of allowance	0	0
Observable Market Data (Level 2) \| Consumer
Financial assets:
Loans receivable, net of allowance	0	0
Company Determined Fair Value (Level 3)
Financial assets:
Held-to-maturity Securities, Fair Value	0	0
Mortgage servicing rights	1,840	1,766
Financial liabilities:
Time deposits	0	0
Short-term Debt, Fair Value	0	0
Long-term Debt, Fair Value	0	0
Subordinated debentures	0	0
Company Determined Fair Value (Level 3) \| Residential Real Estate
Financial assets:
Loans receivable, net of allowance	842,132	853,056
Company Determined Fair Value (Level 3) \| Commercial Real Estate
Financial assets:
Loans receivable, net of allowance	1,119,406	1,115,618
Company Determined Fair Value (Level 3) \| Commercial
Financial assets:
Loans receivable, net of allowance	404,925	401,902
Company Determined Fair Value (Level 3) \| Home Equity
Financial assets:
Loans receivable, net of allowance	311,142	318,230
Company Determined Fair Value (Level 3) \| Consumer
Financial assets:
Loans receivable, net of allowance	16,880	17,335
Carrying Amount
Financial assets:
Held-to-maturity securities, at amortized cost	93,192	94,073
Mortgage servicing rights	972	1,025
Financial liabilities:
Time deposits	538,957	517,032
Short-term Debt, Fair Value	552,624	541,796
Long-term Debt, Fair Value	10,773	10,791
Subordinated debentures	58,950	58,911
Carrying Amount \| Residential Real Estate
Financial assets:
Loans receivable, net of allowance	855,036	853,283
Carrying Amount \| Commercial Real Estate
Financial assets:
Loans receivable, net of allowance	1,159,247	1,152,160
Carrying Amount \| Commercial
Financial assets:
Loans receivable, net of allowance	415,879	413,898
Carrying Amount \| Home Equity
Financial assets:
Loans receivable, net of allowance	318,215	321,011
Carrying Amount \| Consumer
Financial assets:
Loans receivable, net of allowance	$ 17,781	$ 17,916

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Fair value of investments in debt securities classified as held-to-maturity.

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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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