5. INVESTMENT SECURITIES - Amortized cost and estimated fair value of investment securities (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Debt securities:
Amortized Cost	$ 283,446	$ 270,919
Gross Unrealized Gains	6,240	4,373
Gross Unrealized Losses	(622)	(2,501)
Estimated Fair Value	289,064us-gaap_AvailableForSaleSecurities	272,791us-gaap_AvailableForSaleSecurities
US Government Agencies and Sponsored Agencies
Debt securities:
Amortized Cost	257,002	243,058
Gross Unrealized Gains	4,715	3,429
Gross Unrealized Losses	(602)	(2,327)
Estimated Fair Value	261,115	244,160
Obligations of states and political subdivisions
Debt securities:
Amortized Cost	24,886	26,302
Gross Unrealized Gains	1,423	775
Gross Unrealized Losses	(20)	(174)
Estimated Fair Value	26,289	26,903
Corporate Debt Securities
Debt securities:
Amortized Cost	1,504	1,505
Gross Unrealized Gains	79	104
Gross Unrealized Losses
Estimated Fair Value	1,583	1,609
Corporate stock
Debt securities:
Amortized Cost	54	54
Gross Unrealized Gains	23	65
Gross Unrealized Losses
Estimated Fair Value	$ 77	$ 119

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This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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- Definition

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

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Amount of unrealized gain before deducting unrealized loss on investments in debt and equity securities classified as available-for-sale securities.

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Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities.

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