INVESTMENTS IN DEBT AND EQUITY SECURITIES (Schedule of Continuous Unrealized Losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Held To Maturity, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	$ 249,837	$ 29,012
Continuous unrealized loss position less than 12 months, gross unrealized losses	(3,368)	(115)
Continuous unrealized loss position 12 months or more, fair value	114,765	326,716
Continuous unrealized loss position 12 months or more, gross unrealized losses	(2,360)	(5,735)
Continuous unrealized loss position total, fair value	364,602	355,728
Continuous unrealized loss position total, gross unrealized losses	(5,728)	(5,850)
Available For Sale, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	385,940	323,350
Continuous unrealized loss position less than 12 months, gross unrealized losses	(3,324)	(2,187)
Continuous unrealized loss position 12 months or more, fair value	106,789	211,199
Continuous unrealized loss position 12 months or more, gross unrealized losses	(2,125)	(5,138)
Continuous unrealized loss position total, fair value	492,729	534,549
Continuous unrealized loss position total, gross unrealized losses	(5,449)	(7,325)
U.S. Government sponsored agencies [Member]
Available For Sale, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	87,514	79,207
Continuous unrealized loss position less than 12 months, gross unrealized losses	(1,099)	(427)
Continuous unrealized loss position 12 months or more, fair value	14,600	14,600
Continuous unrealized loss position 12 months or more, gross unrealized losses	(139)	(130)
Continuous unrealized loss position total, fair value	102,114	93,807
Continuous unrealized loss position total, gross unrealized losses	(1,238)	(557)
Residential mortgage-backed [Member]
Available For Sale, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	194,279	204,378
Continuous unrealized loss position less than 12 months, gross unrealized losses	(922)	(1,154)
Continuous unrealized loss position 12 months or more, fair value	85,274	191,644
Continuous unrealized loss position 12 months or more, gross unrealized losses	(1,901)	(4,963)
Continuous unrealized loss position total, fair value	279,553	396,022
Continuous unrealized loss position total, gross unrealized losses	(2,823)	(6,117)
Commercial mortgage-backed [Member]
Available For Sale, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	8,803
Continuous unrealized loss position less than 12 months, gross unrealized losses	(2)
Continuous unrealized loss position 12 months or more, fair value	0
Continuous unrealized loss position 12 months or more, gross unrealized losses	0
Continuous unrealized loss position total, fair value	8,803
Continuous unrealized loss position total, gross unrealized losses	(2)
State and political subdivisions [Member]
Available For Sale, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	28,049	28,148
Continuous unrealized loss position less than 12 months, gross unrealized losses	(292)	(223)
Continuous unrealized loss position 12 months or more, fair value	0	0
Continuous unrealized loss position 12 months or more, gross unrealized losses	0	0
Continuous unrealized loss position total, fair value	28,049	28,148
Continuous unrealized loss position total, gross unrealized losses	(292)	(223)
Corporate notes [Member]
Available For Sale, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	67,295	9,650
Continuous unrealized loss position less than 12 months, gross unrealized losses	(1,009)	(350)
Continuous unrealized loss position 12 months or more, fair value	4,959	4,955
Continuous unrealized loss position 12 months or more, gross unrealized losses	(41)	(45)
Continuous unrealized loss position total, fair value	72,254	14,605
Continuous unrealized loss position total, gross unrealized losses	(1,050)	(395)
Equity investments [Member]
Available For Sale, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	0	1,967
Continuous unrealized loss position less than 12 months, gross unrealized losses	0	(33)
Continuous unrealized loss position 12 months or more, fair value	1,956	0
Continuous unrealized loss position 12 months or more, gross unrealized losses	(44)	0
Continuous unrealized loss position total, fair value	1,956	1,967
Continuous unrealized loss position total, gross unrealized losses	(44)	(33)
Residential mortgage-backed [Member]
Held To Maturity, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	246,432	28,371
Continuous unrealized loss position less than 12 months, gross unrealized losses	(3,277)	(112)
Continuous unrealized loss position 12 months or more, fair value	114,765	325,820
Continuous unrealized loss position 12 months or more, gross unrealized losses	(2,360)	(5,670)
Continuous unrealized loss position total, fair value	361,197	354,191
Continuous unrealized loss position total, gross unrealized losses	(5,637)	(5,782)
State and political subdivisions [Member]
Held To Maturity, Continuous Unrealized Loss Position [Abstract]
Continuous unrealized loss position less than 12 months, fair value	3,405	641
Continuous unrealized loss position less than 12 months, gross unrealized losses	(91)	(3)
Continuous unrealized loss position 12 months or more, fair value	0	896
Continuous unrealized loss position 12 months or more, gross unrealized losses	0	(65)
Continuous unrealized loss position total, fair value	3,405	1,537
Continuous unrealized loss position total, gross unrealized losses	$ (91)	$ (68)