SECURITIES (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities
Amortized Cost	$ 1,075,235	$ 675,474
Gross Unrealized Gains	28,737	11,701
Gross Unrealized (Losses)	(1,858)	(9,827)
Total securities available for sale, Estimated Fair Value	1,102,114us-gaap_AvailableForSaleSecurities	677,348us-gaap_AvailableForSaleSecurities
US Government Agencies Debt Securities [Member]
Amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities
Amortized Cost	8,313	1,654
Gross Unrealized Gains	166	499
Gross Unrealized (Losses)	(25)
Total securities available for sale, Estimated Fair Value	8,454	2,153
Obligations of States and Political Subdivisions [Member]
Amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities
Amortized Cost	427,483	255,335
Gross Unrealized Gains	18,885	6,107
Gross Unrealized (Losses)	(721)	(6,612)
Total securities available for sale, Estimated Fair Value	445,647	254,830
Corporate and Other Bonds [Member]
Amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities
Amortized Cost	78,744	9,479
Gross Unrealized Gains	244	115
Gross Unrealized (Losses)	(308)	(160)
Total securities available for sale, Estimated Fair Value	78,680	9,434
Mortgage Backed Securities [Member]
Amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities
Amortized Cost	550,716	405,389
Gross Unrealized Gains	9,411	4,954
Gross Unrealized (Losses)	(798)	(2,981)
Total securities available for sale, Estimated Fair Value	559,329	407,362
Other Securities [Member]
Amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities
Amortized Cost	9,979	3,617
Gross Unrealized Gains	31	26
Gross Unrealized (Losses)	(6)	(74)
Total securities available for sale, Estimated Fair Value	$ 10,004	$ 3,569

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

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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

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-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

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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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