INVESTMENT SECURITIES, Investment Portfolio (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Net unrealized gain (loss) on investment portfolio	$ 5,900,000	$ (24,500,000)
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	1,193,707,000	1,692,885,000
Continuous unrealized loss position less than 12 months, unrealized losses	(16,463,000)	(29,417,000)
Continuous unrealized loss position 12 months or more, fair value	50,241,000	16,180,000
Continuous unrealized loss position 12 months or more, unrealized losses	(9,958,000)	(19,435,000)
Continuous unrealized loss position total, fair value	1,243,948,000	1,709,065,000
Continuous unrealized loss position total, unrealized losses	(26,421,000)	(48,852,000)
US Treasury Securities [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	0	0
Continuous unrealized loss position less than 12 months, unrealized losses	0	0
Continuous unrealized loss position 12 months or more, fair value	0	0
Continuous unrealized loss position 12 months or more, unrealized losses	0	0
Continuous unrealized loss position total, fair value	0	0
Continuous unrealized loss position total, unrealized losses	0	0
US Government Agencies and Government Sponsored Enterprise Debt Securities [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	428,712,000	935,654,000
Continuous unrealized loss position less than 12 months, unrealized losses	(3,794,000)	(18,121,000)
Continuous unrealized loss position 12 months or more, fair value	0	0
Continuous unrealized loss position 12 months or more, unrealized losses	0	0
Continuous unrealized loss position total, fair value	428,712,000	935,654,000
Continuous unrealized loss position total, unrealized losses	(3,794,000)	(18,121,000)
Commercial Mortgage Backed Securities Issued By US Government Agencies And Government Sponsored Enterprise [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	0	0
Continuous unrealized loss position less than 12 months, unrealized losses	0	0
Continuous unrealized loss position 12 months or more, fair value	0	0
Continuous unrealized loss position 12 months or more, unrealized losses	0	0
Continuous unrealized loss position total, fair value	0	0
Continuous unrealized loss position total, unrealized losses	0	0
Residential Mortgage Backed Securities Issued By US Government Agencies And Government Sponsored Enterprise [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	101,766,000	0
Continuous unrealized loss position less than 12 months, unrealized losses	(304,000)	0
Continuous unrealized loss position 12 months or more, fair value	0	0
Continuous unrealized loss position 12 months or more, unrealized losses	0	0
Continuous unrealized loss position total, fair value	101,766,000	0
Continuous unrealized loss position total, unrealized losses	(304,000)	0
Municipal Securities [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	5,479,000	0
Continuous unrealized loss position less than 12 months, unrealized losses	(87,000)	0
Continuous unrealized loss position 12 months or more, fair value	0	0
Continuous unrealized loss position 12 months or more, unrealized losses	0	0
Continuous unrealized loss position total, fair value	5,479,000	0
Continuous unrealized loss position total, unrealized losses	(87,000)	0
Other Residential Mortgage-Backed Securities [Member] | Investment Grade [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	0	0
Continuous unrealized loss position less than 12 months, unrealized losses	0	0
Continuous unrealized loss position 12 months or more, fair value	0	0
Continuous unrealized loss position 12 months or more, unrealized losses	0	0
Continuous unrealized loss position total, fair value	0	0
Continuous unrealized loss position total, unrealized losses	0	0
Other Residential Mortgage-Backed Securities [Member] | Non-investment Grade [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	0	0
Continuous unrealized loss position less than 12 months, unrealized losses	0	0
Continuous unrealized loss position 12 months or more, fair value	0	6,254,000
Continuous unrealized loss position 12 months or more, unrealized losses	0	(8,742,000)
Continuous unrealized loss position total, fair value	0	6,254,000
Continuous unrealized loss position total, unrealized losses	0	(8,742,000)
Corporate Debt Securities [Member] | Investment Grade [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	650,004,000	656,434,000
Continuous unrealized loss position less than 12 months, unrealized losses	(12,088,000)	(8,765,000)
Continuous unrealized loss position 12 months or more, fair value	39,531,000	0
Continuous unrealized loss position 12 months or more, unrealized losses	(452,000)	0
Continuous unrealized loss position total, fair value	689,535,000	656,434,000
Continuous unrealized loss position total, unrealized losses	(12,540,000)	(8,765,000)
Corporate Debt Securities [Member] | Non-investment Grade [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	5,786,000	24,105,000
Continuous unrealized loss position less than 12 months, unrealized losses	(178,000)	(623,000)
Continuous unrealized loss position 12 months or more, fair value	10,710,000	9,926,000
Continuous unrealized loss position 12 months or more, unrealized losses	(9,506,000)	(10,693,000)
Continuous unrealized loss position total, fair value	16,496,000	34,031,000
Continuous unrealized loss position total, unrealized losses	(9,684,000)	(11,316,000)
Other Securities [Member]
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	1,960,000	76,692,000
Continuous unrealized loss position less than 12 months, unrealized losses	(12,000)	(1,908,000)
Continuous unrealized loss position 12 months or more, fair value	0	0
Continuous unrealized loss position 12 months or more, unrealized losses	0	0
Continuous unrealized loss position total, fair value	1,960,000	76,692,000
Continuous unrealized loss position total, unrealized losses	$ (12,000)	$ (1,908,000)