INVESTMENTS IN DEBT AND EQUITY SECURITIES (Schedule of Available For Sale and Held To Maturity Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity debt securities, amortized cost	$ 595,177	$ 618,148
Held to maturity securities, gross unrealized gains	5,049	1,974
Held to maturity securities, gross unrealized losses	(4,411)	(5,850)
Held to maturity debt securities, fair value	595,815	614,272
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, amortized cost	1,319,967	1,433,846
Available for sale securities, gross unrealized gains	17,810	19,168
Available for sale securities, gross unrealized losses	(7,820)	(7,325)
Available for sale securities, fair value	1,329,957	1,445,689
U.S. Government sponsored agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, amortized cost	230,335	230,159
Available for sale securities, gross unrealized gains	2	2,129
Available for sale securities, gross unrealized losses	(4,235)	(557)
Available for sale securities, fair value	226,102	231,731
Residential mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, amortized cost	863,930	999,772
Available for sale securities, gross unrealized gains	16,508	14,189
Available for sale securities, gross unrealized losses	(1,428)	(6,117)
Available for sale securities, fair value	879,010	1,007,844
Commercial mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, amortized cost	20,101	779
Available for sale securities, gross unrealized gains	181	58
Available for sale securities, gross unrealized losses	(9)	0
Available for sale securities, fair value	20,273	837
State and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, amortized cost	28,867	29,805
Available for sale securities, gross unrealized gains	13	33
Available for sale securities, gross unrealized losses	(880)	(223)
Available for sale securities, fair value	28,000	29,615
Corporate notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, amortized cost	174,734	171,331
Available for sale securities, gross unrealized gains	1,106	2,759
Available for sale securities, gross unrealized losses	(1,244)	(395)
Available for sale securities, fair value	174,596	173,695
Equity investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, amortized cost	2,000	2,000
Available for sale securities, gross unrealized gains	0	0
Available for sale securities, gross unrealized losses	(24)	(33)
Available for sale securities, fair value	1,976	1,967
U.S. Government sponsored agencies [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity debt securities, amortized cost	8,345	10,725
Held to maturity securities, gross unrealized gains	55	42
Held to maturity securities, gross unrealized losses	0	0
Held to maturity debt securities, fair value	8,400	10,767
Residential mortgage-backed [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity debt securities, amortized cost	581,828	605,077
Held to maturity securities, gross unrealized gains	4,993	1,931
Held to maturity securities, gross unrealized losses	(4,315)	(5,782)
Held to maturity debt securities, fair value	582,506	601,226
State and political subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity debt securities, amortized cost	5,004	2,346
Held to maturity securities, gross unrealized gains	1	1
Held to maturity securities, gross unrealized losses	(96)	(68)
Held to maturity debt securities, fair value	$ 4,909	$ 2,279

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