SECURITIES (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 931,034	$ 891,276
Gross Unrealized Gains	26,253	16,661
Gross Unrealized (Losses)	(2,303)	(4,645)
Estimated Fair Value	954,984	903,292
Obligations of States and Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	266,291	257,740
Gross Unrealized Gains	13,147	10,479
Gross Unrealized (Losses)	(215)	(140)
Estimated Fair Value	279,223	268,079
Corporate and Other Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	122,130	77,628
Gross Unrealized Gains	1,196	55
Gross Unrealized (Losses)	(1,579)	(1,704)
Estimated Fair Value	121,747	75,979
Mortgage-Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	529,228	544,823
Gross Unrealized Gains	11,877	6,127
Gross Unrealized (Losses)	(509)	(2,779)
Estimated Fair Value	540,596	548,171
Other Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,385	11,085
Gross Unrealized Gains	33	0
Gross Unrealized (Losses)	0	(22)
Estimated Fair Value	$ 13,418	$ 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=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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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.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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