SECURITIES (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities, Amortized Cost Basis, Total	$ 947,597	$ 891,276
Gross Unrealized Gains	10,480	16,661
Gross Unrealized (Losses)	(11,313)	(4,645)
Available for sale securities, Estimated fair value	946,764	903,292
Obligations of states and political subdivisions
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities, Amortized Cost Basis, Total	274,007	257,740
Gross Unrealized Gains	4,962	10,479
Gross Unrealized (Losses)	(3,079)	(140)
Available for sale securities, Estimated fair value	275,890	268,079
Corporate bonds
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities, Amortized Cost Basis, Total	123,674	77,628
Gross Unrealized Gains	892	55
Gross Unrealized (Losses)	(2,786)	(1,704)
Available for sale securities, Estimated fair value	121,780	75,979
Mortgage-backed securities
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities, Amortized Cost Basis, Total	536,031	544,823
Gross Unrealized Gains	4,626	6,127
Gross Unrealized (Losses)	(5,371)	(2,779)
Available for sale securities, Estimated fair value	535,286	548,171
Other securities
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities, Amortized Cost Basis, Total	13,885	11,085
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	(77)	(22)
Available for sale securities, Estimated fair value	$ 13,808	$ 11,063

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
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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This item represents the cost of debt and equity 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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