INVESTMENT SECURITIES (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	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	$ 419,613		$ 419,613		$ 1,803,074
Continuous unrealized loss position less than 12 months, unrealized losses			(3,377)		(45,167)
Continuous unrealized loss position 12 months or more, fair value	957,984		957,984		250,361
Continuous unrealized loss position 12 months or more, unrealized losses			(20,709)		(19,729)
Continuous unrealized loss position total, fair value	1,377,597		1,377,597		2,053,435
Continuous unrealized loss position total, unrealized losses			(24,086)		(64,896)
Impairment Loss	0	0	0	0	0
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	130,631		130,631		337,248
Continuous unrealized loss position less than 12 months, unrealized losses			(276)		(3,622)
Continuous unrealized loss position 12 months or more, fair value	183,673		183,673
Continuous unrealized loss position 12 months or more, unrealized losses			(2,077)
Continuous unrealized loss position total, fair value	314,304		314,304		337,248
Continuous unrealized loss position total, unrealized losses			(2,353)		(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	108,393		108,393		387,097
Continuous unrealized loss position less than 12 months, unrealized losses			(1,281)		(12,726)
Continuous unrealized loss position 12 months or more, fair value	172,113		172,113
Continuous unrealized loss position 12 months or more, unrealized losses			(3,006)
Continuous unrealized loss position total, fair value	280,506		280,506		387,097
Continuous unrealized loss position total, unrealized losses			(4,287)		(12,726)
Total investment securities available-for-sale portfolio (as a percent)	16.00%		16.00%		14.00%
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	52,082		52,082		114,754
Continuous unrealized loss position less than 12 months, unrealized losses			(655)		(3,280)
Continuous unrealized loss position 12 months or more, fair value	28,859		28,859		16,065
Continuous unrealized loss position 12 months or more, unrealized losses			(899)		(1,169)
Continuous unrealized loss position total, fair value	80,941		80,941		130,819
Continuous unrealized loss position total, unrealized losses			(1,554)		(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	107,182		107,182		502,285
Continuous unrealized loss position less than 12 months, unrealized losses			(616)		(10,570)
Continuous unrealized loss position 12 months or more, fair value	326,003		326,003		92,540
Continuous unrealized loss position 12 months or more, unrealized losses			(7,442)		(4,357)
Continuous unrealized loss position total, fair value	433,185		433,185		594,825
Continuous unrealized loss position total, unrealized losses			(8,058)		(14,927)
Total investment securities available-for-sale portfolio (as a percent)	29.00%		29.00%		32.00%
Municipal securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	5,260		5,260		173,782
Continuous unrealized loss position less than 12 months, unrealized losses			(14)		(10,765)
Continuous unrealized loss position 12 months or more, fair value	108,407		108,407		47,892
Continuous unrealized loss position 12 months or more, unrealized losses			(2,521)		(6,768)
Continuous unrealized loss position total, fair value	113,667		113,667		221,674
Continuous unrealized loss position total, unrealized losses			(2,535)		(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	14,054		14,054
Continuous unrealized loss position 12 months or more, unrealized losses			(356)
Continuous unrealized loss position total, fair value	14,054		14,054		46,328
Continuous unrealized loss position total, unrealized losses			(356)		(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
Continuous unrealized loss position less than 12 months, unrealized losses					(1,538)
Continuous unrealized loss position 12 months or more, fair value	109,695		109,695		79,442
Continuous unrealized loss position 12 months or more, unrealized losses			(1,445)		(1,806)
Continuous unrealized loss position total, fair value	109,695		109,695		272,924
Continuous unrealized loss position total, unrealized losses			(1,445)		(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	15,180		15,180		14,422
Continuous unrealized loss position 12 months or more, unrealized losses			(2,963)		(5,629)
Continuous unrealized loss position total, fair value	15,180		15,180		14,422
Continuous unrealized loss position total, unrealized losses			(2,963)		(5,629)
Total investment securities available-for-sale portfolio (as a percent)	1.00%		1.00%		1.00%
Other securities
Continuous unrealized loss position, fair values of investment securities available-for-sale
Continuous unrealized loss position less than 12 months, fair value	16,065		16,065		48,098
Continuous unrealized loss position less than 12 months, unrealized losses			(535)		(864)
Continuous unrealized loss position total, fair value	16,065		16,065		48,098
Continuous unrealized loss position total, unrealized losses			$ (535)		$ (864)