INVESTMENT SECURITIES (Details 5) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014 item		Dec. 31, 2013 item
Schedule of Available-for-sale Securities
Fair value of available for sale securities	$ 2,474,744		$ 2,733,797
Number of securities in a continuous unrealized loss position for more than twelve months	75		65
Unrealized losses in loss position for twelve months or more	(17,551)		(19,729)
Number of individual securities with a continuous unrealized loss position less than 12 months	179		239
Unrealized losses in loss position for less than twelve months	(27,692)		(45,167)
Continuous unrealized loss position 12 months or more, fair value	294,599		250,361
US Government Agencies and Government Sponsored Enterprise Debt Securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities			394,300
Total investment securities available-for-sale portfolio (as a percent)	16.00%		14.00%
Number of individual securities with a continuous unrealized loss position less than 12 months	9		16
U.S. Government agency and U.S. Government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	824,105		885,237
Total investment securities available-for-sale portfolio (as a percent)	33.00%		32.00%
Number of securities in a continuous unrealized loss position for more than twelve months	23		21
Unrealized losses in loss position for twelve months or more	(4,784)		(4,357)
Number of individual securities with a continuous unrealized loss position less than 12 months	47		55
Unrealized losses in loss position for less than twelve months	(7,447)		(10,570)
Continuous unrealized loss position 12 months or more, fair value	119,255		92,540
Municipal securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	283,897		280,979
Total investment securities available-for-sale portfolio (as a percent)	11.00%		10.00%
Number of securities in a continuous unrealized loss position for more than twelve months	40		32
Unrealized losses in loss position for twelve months or more	(5,079)		(6,768)
Number of individual securities with a continuous unrealized loss position less than 12 months	62		94
Unrealized losses in loss position for less than twelve months	(4,462)		(10,765)
Continuous unrealized loss position 12 months or more, fair value	64,839		47,892
Trust Preferred Securities
Schedule of Available-for-sale Securities
Number of securities in a continuous unrealized loss position for more than twelve months			5
Unrealized losses in loss position for twelve months or more			(14,400)
Number of individual securities with a continuous unrealized loss position less than 12 months	5
Continuous unrealized loss position 12 months or more, fair value			14,400
Trust Preferred Securities | Non-investment grade
Schedule of Available-for-sale Securities
Total investment securities available-for-sale portfolio (as a percent)	1.00%
Number of securities in a continuous unrealized loss position for more than twelve months	5
Continuous unrealized loss position 12 months or more, fair value	14,900
Other securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	101,068		79,716
Number of individual securities with a continuous unrealized loss position less than 12 months	3		9
Unrealized losses in loss position for less than twelve months	(619)		(864)
Corporate debt securities | Investment grade
Schedule of Available-for-sale Securities
Fair value of available for sale securities	209,691		309,995
Number of securities in a continuous unrealized loss position for more than twelve months	4		4
Unrealized losses in loss position for twelve months or more	(1,686)		(1,806)
Number of individual securities with a continuous unrealized loss position less than 12 months	5		8
Unrealized losses in loss position for less than twelve months	(1,276)		(1,538)
Continuous unrealized loss position 12 months or more, fair value	79,554		79,442
Corporate debt securities | Non-investment grade
Schedule of Available-for-sale Securities
Fair value of available for sale securities	15,512	[1]	15,101	[1]
Unrealized losses in loss position for twelve months or more	(5,093)		(5,629)
Continuous unrealized loss position 12 months or more, fair value	14,869		14,422
Percentage of total amortized cost basis of these securities	26.00%
U.S. Treasury securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	428,253		491,632
Number of individual securities with a continuous unrealized loss position less than 12 months	34		33
Unrealized losses in loss position for less than twelve months	(3,145)		(3,622)
U.S. Government agency and U.S. Government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	119,107		178,870
Number of securities in a continuous unrealized loss position for more than twelve months	3		3
Unrealized losses in loss position for twelve months or more	(909)		(1,169)
Number of individual securities with a continuous unrealized loss position less than 12 months	13		19
Unrealized losses in loss position for less than twelve months	(1,752)		(3,280)
Continuous unrealized loss position 12 months or more, fair value	16,082		16,065
Other residential mortgage-backed securities: | Investment grade
Schedule of Available-for-sale Securities
Fair value of available for sale securities	57,007		46,327
Number of individual securities with a continuous unrealized loss position less than 12 months	6		5
Unrealized losses in loss position for less than twelve months	(1,443)		(1,802)
Other commercial mortgage-backed securities: | Investment grade
Schedule of Available-for-sale Securities
Fair value of available for sale securities	$ 51,419		$ 51,617

[1] For the three months ended March 31, 2014 and the year ended December 31, 2013, the Company did not record any OTTI.