INVESTMENT SECURITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 804,680	$ 533,219	$ 524,792
Gross Unrealized Gains	9,259	10,697	8,438
Gross Unrealized Losses	(2,554)	(2,111)	(3,721)
Fair Value	811,385	541,805	529,509
U.S. government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,957	14,953	14,951
Gross Unrealized Gains	26	0	0
Gross Unrealized Losses	(15)	(275)	(491)
Fair Value	14,968	14,678	14,460
State, county and municipal securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	161,509	137,873	134,641
Gross Unrealized Gains	3,875	3,935	3,708
Gross Unrealized Losses	(519)	(433)	(714)
Fair Value	164,865	141,375	137,635
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,901	10,812	10,801
Gross Unrealized Gains	150	228	237
Gross Unrealized Losses	(19)	0	(73)
Fair Value	6,032	11,040	10,965
Mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	622,313	369,581	364,399
Gross Unrealized Gains	5,208	6,534	4,493
Gross Unrealized Losses	(2,001)	(1,403)	(2,443)
Fair Value	$ 625,520	$ 374,712	$ 366,449