INVESTMENT SECURITIES (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Available-for-Sale Portfolio [Abstract]
Amortized Cost	$ 2,761,022	$ 2,397,886
Gross Unrealized Gains	64,048	77,293
Gross Unrealized Losses	7,209	2,254
Fair Value	2,817,861	2,472,925
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized Cost	2,760,772
Fair Value	2,817,436
Other Securities [Abstract]
Amortized Cost	50,189	40,049
Fair Value	50,189	40,049
U.S. Treasury and Agency Obligations [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized Cost	1,861,584	1,479,134
Gross Unrealized Gains	34,939	39,509
Gross Unrealized Losses	3,078	910
Fair Value	1,893,445	1,517,733
Obligations of State and Political Subdivisions [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized Cost	645,271	645,398
Gross Unrealized Gains	20,092	26,749
Gross Unrealized Losses	2,599	244
Fair Value	662,764	671,903
Government Agency Mortgage-Backed Securities [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized Cost	212,145	228,971
Gross Unrealized Gains	8,080	9,782
Gross Unrealized Losses	1,470	1,025
Fair Value	218,755	237,728
Corporate Debt Securities [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized Cost	26,738	26,803
Gross Unrealized Gains	141	363
Gross Unrealized Losses	62	75
Fair Value	26,817	27,091
Government Agency Collateralized Mortgage Obligations [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized Cost	15,034	17,330
Gross Unrealized Gains	621	695
Gross Unrealized Losses	0	0
Fair Value	15,655	18,025
Marketable Equity Securities [Member]
Available For Sale Equity Securities Amortized Cost Basis [Abstract]
Amortized Cost	250	250
Gross Unrealized Gains	175	195
Gross Unrealized Losses	0	0
Fair Value	425	445
Federal Home Loan Bank Common Stock [Member]
Other Securities [Abstract]
Amortized Cost	29,864	19,553
Fair Value	29,864	19,553
Federal Reserve Bank Common Stock [Member]
Other Securities [Abstract]
Amortized Cost	16,050	16,050
Fair Value	16,050	16,050
Other Equity Securities [Member]
Other Securities [Abstract]
Amortized Cost	4,275	4,446
Fair Value	$ 4,275	$ 4,446

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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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