INVESTMENT SECURITIES, Investment Portfolio (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Continuous unrealized loss position, fair values of investment securities available-for-sale [Abstract]
Continuous unrealized loss position less than 12 months, fair value	$ 1,337,085	$ 1,692,885
Continuous unrealized loss position less than 12 months, unrealized losses	(63,610)	(29,417)
Continuous unrealized loss position 12 months or more, fair value	255,636	16,180
Continuous unrealized loss position 12 months or more, unrealized losses	(24,556)	(19,435)
Continuous unrealized loss position total, fair value	1,592,721	1,709,065
Continuous unrealized loss position total, unrealized losses	(88,166)	(48,852)
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	177,715	935,654
Continuous unrealized loss position less than 12 months, unrealized losses	(708)	(18,121)
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	177,715	935,654
Continuous unrealized loss position total, unrealized losses	(708)	(18,121)
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	195,248	0
Continuous unrealized loss position less than 12 months, unrealized losses	(1,067)	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	195,248	0
Continuous unrealized loss position total, unrealized losses	(1,067)	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	9,715	0
Continuous unrealized loss position less than 12 months, unrealized losses	(133)	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	9,715	0
Continuous unrealized loss position total, unrealized losses	(133)	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
Continuous unrealized loss position 12 months or more, unrealized losses	0	(8,742)
Continuous unrealized loss position total, fair value	0	6,254
Continuous unrealized loss position total, unrealized losses	0	(8,742)
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	944,337	656,434
Continuous unrealized loss position less than 12 months, unrealized losses	(61,314)	(8,765)
Continuous unrealized loss position 12 months or more, fair value	247,020	0
Continuous unrealized loss position 12 months or more, unrealized losses	(12,963)	0
Continuous unrealized loss position total, fair value	1,191,357	656,434
Continuous unrealized loss position total, unrealized losses	(74,277)	(8,765)
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	5,580	24,105
Continuous unrealized loss position less than 12 months, unrealized losses	(387)	(623)
Continuous unrealized loss position 12 months or more, fair value	8,616	9,926
Continuous unrealized loss position 12 months or more, unrealized losses	(11,593)	(10,693)
Continuous unrealized loss position total, fair value	14,196	34,031
Continuous unrealized loss position total, unrealized losses	(11,980)	(11,316)
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	4,490	76,692
Continuous unrealized loss position less than 12 months, unrealized losses	(1)	(1,908)
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	4,490	76,692
Continuous unrealized loss position total, unrealized losses	$ (1)	$ (1,908)