INVESTMENT SECURITIES (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	$ 620,165	$ 1,108,347
Continuous unrealized loss position less than 12 months, unrealized losses	(6,989)	(63,558)
Continuous unrealized loss position 12 months or more, fair value	195,271	359,776
Continuous unrealized loss position 12 months or more, unrealized losses	(19,739)	(44,188)
Continuous unrealized loss position total, fair value	815,436	1,468,123
Continuous unrealized loss position total, unrealized losses	(26,728)	(107,746)
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	95,232
Continuous unrealized loss position less than 12 months, unrealized losses	(71)
Continuous unrealized loss position total, fair value	95,232
Continuous unrealized loss position total, unrealized losses	(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	24,912	143,265
Continuous unrealized loss position less than 12 months, unrealized losses	(82)	(279)
Continuous unrealized loss position total, fair value	24,912	143,265
Continuous unrealized loss position total, unrealized losses	(82)	(279)
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	10,013
Continuous unrealized loss position less than 12 months, unrealized losses	(36)
Continuous unrealized loss position total, fair value	10,013
Continuous unrealized loss position total, unrealized losses	(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	215,826	195,393
Continuous unrealized loss position less than 12 months, unrealized losses	(678)	(772)
Continuous unrealized loss position total, fair value	215,826	195,393
Continuous unrealized loss position total, unrealized losses	(678)	(772)
Municipal securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	48,363	1,158
Continuous unrealized loss position less than 12 months, unrealized losses	(731)	(5)
Continuous unrealized loss position total, fair value	48,363	1,158
Continuous unrealized loss position total, unrealized losses	(731)	(5)
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	225,819	754,055
Continuous unrealized loss position less than 12 months, unrealized losses	(5,391)	(61,935)
Continuous unrealized loss position 12 months or more, fair value	182,697	350,181
Continuous unrealized loss position 12 months or more, unrealized losses	(12,181)	(33,675)
Continuous unrealized loss position total, fair value	408,516	1,104,236
Continuous unrealized loss position total, unrealized losses	(17,572)	(95,610)
Corporate debt securities | Non-investment grade
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value		9,973
Continuous unrealized loss position less than 12 months, unrealized losses		(565)
Continuous unrealized loss position 12 months or more, fair value	12,574	9,595
Continuous unrealized loss position 12 months or more, unrealized losses	(7,558)	(10,513)
Continuous unrealized loss position total, fair value	12,574	19,568
Continuous unrealized loss position total, unrealized losses	(7,558)	(11,078)
Other securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value		4,503
Continuous unrealized loss position less than 12 months, unrealized losses		(2)
Continuous unrealized loss position total, fair value		4,503
Continuous unrealized loss position total, unrealized losses		$ (2)