INVESTMENT SECURITIES (Details 4) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	$ 333,289	$ 1,803,074
Continuous unrealized loss position less than 12 months, unrealized losses	(3,939)	(45,167)
Continuous unrealized loss position 12 months or more, fair value	966,358	250,361
Continuous unrealized loss position 12 months or more, unrealized losses	(22,713)	(19,729)
Continuous unrealized loss position total, fair value	1,299,647	2,053,435
Continuous unrealized loss position total, unrealized losses	(26,652)	(64,896)
U.S. Treasury securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	30,630	337,248
Continuous unrealized loss position less than 12 months, unrealized losses	(40)	(3,622)
Continuous unrealized loss position 12 months or more, fair value	184,740
Continuous unrealized loss position 12 months or more, unrealized losses	(1,588)
Continuous unrealized loss position total, fair value	215,370	337,248
Continuous unrealized loss position total, unrealized losses	(1,628)	(3,622)
U.S. government agency and U.S. government sponsored enterprise debt securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	33,829	387,097
Continuous unrealized loss position less than 12 months, unrealized losses	(882)	(12,726)
Continuous unrealized loss position 12 months or more, fair value	171,913
Continuous unrealized loss position 12 months or more, unrealized losses	(3,204)
Continuous unrealized loss position total, fair value	205,742	387,097
Continuous unrealized loss position total, unrealized losses	(4,086)	(12,726)
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	23,683	114,754
Continuous unrealized loss position less than 12 months, unrealized losses	(513)	(3,280)
Continuous unrealized loss position 12 months or more, fair value	43,550	16,065
Continuous unrealized loss position 12 months or more, unrealized losses	(850)	(1,169)
Continuous unrealized loss position total, fair value	67,233	130,819
Continuous unrealized loss position total, unrealized losses	(1,363)	(4,449)
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	205,095	502,285
Continuous unrealized loss position less than 12 months, unrealized losses	(1,992)	(10,570)
Continuous unrealized loss position 12 months or more, fair value	306,292	92,540
Continuous unrealized loss position 12 months or more, unrealized losses	(7,065)	(4,357)
Continuous unrealized loss position total, fair value	511,387	594,825
Continuous unrealized loss position total, unrealized losses	(9,057)	(14,927)
Municipal securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	3,949	173,782
Continuous unrealized loss position less than 12 months, unrealized losses	(15)	(10,765)
Continuous unrealized loss position 12 months or more, fair value	138,062	47,892
Continuous unrealized loss position 12 months or more, unrealized losses	(4,632)	(6,768)
Continuous unrealized loss position total, fair value	142,011	221,674
Continuous unrealized loss position total, unrealized losses	(4,647)	(17,533)
Other residential mortgage-backed securities: | Investment grade
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value		46,328
Continuous unrealized loss position less than 12 months, unrealized losses		(1,802)
Continuous unrealized loss position 12 months or more, fair value	14,485
Continuous unrealized loss position 12 months or more, unrealized losses	(416)
Continuous unrealized loss position total, fair value	14,485	46,328
Continuous unrealized loss position total, unrealized losses	(416)	(1,802)
Corporate debt securities | Investment grade
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	19,943	193,482
Continuous unrealized loss position less than 12 months, unrealized losses	(57)	(1,538)
Continuous unrealized loss position 12 months or more, fair value	89,752	79,442
Continuous unrealized loss position 12 months or more, unrealized losses	(1,389)	(1,806)
Continuous unrealized loss position total, fair value	109,695	272,924
Continuous unrealized loss position total, unrealized losses	(1,446)	(3,344)
Corporate debt securities | Non-investment grade
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position 12 months or more, fair value	14,660	14,422
Continuous unrealized loss position 12 months or more, unrealized losses	(3,505)	(5,629)
Continuous unrealized loss position total, fair value	14,660	14,422
Continuous unrealized loss position total, unrealized losses	(3,505)	(5,629)
Other securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	16,160	48,098
Continuous unrealized loss position less than 12 months, unrealized losses	(440)	(864)
Continuous unrealized loss position 12 months or more, fair value	2,904
Continuous unrealized loss position 12 months or more, unrealized losses	(64)
Continuous unrealized loss position total, fair value	19,064	48,098
Continuous unrealized loss position total, unrealized losses	$ (504)	$ (864)