INVESTMENT SECURITIES (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	$ 1,803,074	$ 620,165
Continuous unrealized loss position less than 12 months, unrealized losses	(45,167)	(6,989)
Continuous unrealized loss position 12 months or more, fair value	250,361	195,271
Continuous unrealized loss position 12 months or more, unrealized losses	(19,729)	(19,739)
Continuous unrealized loss position total, fair value	2,053,435	815,436
Continuous unrealized loss position total, unrealized losses	(64,896)	(26,728)
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	337,248	95,232
Continuous unrealized loss position less than 12 months, unrealized losses	(3,622)	(71)
Continuous unrealized loss position total, fair value	337,248	95,232
Continuous unrealized loss position total, unrealized losses	(3,622)	(71)
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	387,097	24,912
Continuous unrealized loss position less than 12 months, unrealized losses	(12,726)	(82)
Continuous unrealized loss position total, fair value	387,097	24,912
Continuous unrealized loss position total, unrealized losses	(12,726)	(82)
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	114,754	10,013
Continuous unrealized loss position less than 12 months, unrealized losses	(3,280)	(36)
Continuous unrealized loss position 12 months or more, fair value	16,065
Continuous unrealized loss position 12 months or more, unrealized losses	(1,169)
Continuous unrealized loss position total, fair value	130,819	10,013
Continuous unrealized loss position total, unrealized losses	(4,449)	(36)
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	502,285	215,826
Continuous unrealized loss position less than 12 months, unrealized losses	(10,570)	(678)
Continuous unrealized loss position 12 months or more, fair value	92,540
Continuous unrealized loss position 12 months or more, unrealized losses	(4,357)
Continuous unrealized loss position total, fair value	594,825	215,826
Continuous unrealized loss position total, unrealized losses	(14,927)	(678)
Municipal securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	173,782	48,363
Continuous unrealized loss position less than 12 months, unrealized losses	(10,765)	(731)
Continuous unrealized loss position 12 months or more, fair value	47,892
Continuous unrealized loss position 12 months or more, unrealized losses	(6,768)
Continuous unrealized loss position total, fair value	221,674	48,363
Continuous unrealized loss position total, unrealized losses	(17,533)	(731)
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 total, fair value	46,328
Continuous unrealized loss position total, unrealized losses	(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	193,482	225,819
Continuous unrealized loss position less than 12 months, unrealized losses	(1,538)	(5,391)
Continuous unrealized loss position 12 months or more, fair value	79,442	182,697
Continuous unrealized loss position 12 months or more, unrealized losses	(1,806)	(12,181)
Continuous unrealized loss position total, fair value	272,924	408,516
Continuous unrealized loss position total, unrealized losses	(3,344)	(17,572)
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	14,422	12,574
Continuous unrealized loss position 12 months or more, unrealized losses	(5,629)	(7,558)
Continuous unrealized loss position total, fair value	14,422	12,574
Continuous unrealized loss position total, unrealized losses	(5,629)	(7,558)
Other securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	48,098
Continuous unrealized loss position less than 12 months, unrealized losses	(864)
Continuous unrealized loss position total, fair value	48,098
Continuous unrealized loss position total, unrealized losses	$ (864)