INVESTMENT SECURITIES (Details 5) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item		Dec. 31, 2011 item	Dec. 31, 2013 item
Schedule of Available-for-sale Securities
Fair value of available for sale securities	$ 2,607,029			$ 2,733,797
Number of securities in a continuous unrealized loss position for more than twelve months	13			65
Unrealized losses in loss position for twelve months or more	(19,739)			(19,729)
Number of individual securities with a continuous unrealized loss position less than 12 months	77			239
Unrealized losses in loss position for less than twelve months	(6,989)			(45,167)
Continuous unrealized loss position 12 months or more, fair value	195,271			250,361
Municipal securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	167,093			280,979
Total investment securities available-for-sale portfolio (as a percent)				10.00%
Number of securities in a continuous unrealized loss position for more than twelve months				32
Unrealized losses in loss position for twelve months or more				(6,768)
Number of individual securities with a continuous unrealized loss position less than 12 months	29			94
Unrealized losses in loss position for less than twelve months	(731)			(10,765)
Continuous unrealized loss position 12 months or more, fair value				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				(5,600)
Noncredit-related impairment losses	99		633
Number of securities for which noncredit-related impairment losses have been recorded during the period	5		5
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	12,600			14,400
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	1,144,085			885,237
Total investment securities available-for-sale portfolio (as a percent)				32.00%
Number of securities in a continuous unrealized loss position for more than twelve months				21
Unrealized losses in loss position for twelve months or more				(4,357)
Number of individual securities with a continuous unrealized loss position less than 12 months	26			55
Unrealized losses in loss position for less than twelve months	(678)			(10,570)
Continuous unrealized loss position 12 months or more, fair value				92,540
Investment Grade Corporate debt and commercial agency mortgage-backed securities
Schedule of Available-for-sale Securities
Number of securities in a continuous unrealized loss position for more than twelve months				7
Unrealized losses in loss position for twelve months or more				(2,900)
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)				14.00%
Number of individual securities with a continuous unrealized loss position less than 12 months	1			16
Unrealized losses in loss position for less than twelve months				(12,700)
Other securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	10,170			79,716
Unrealized losses in loss position for less than twelve months				(864)
Other securities | All other
Schedule of Available-for-sale Securities
Number of individual securities with a continuous unrealized loss position less than 12 months				74
Unrealized losses in loss position for less than twelve months				(11,100)
Corporate debt securities | Investment grade
Schedule of Available-for-sale Securities
Fair value of available for sale securities	411,983			309,995
Number of securities in a continuous unrealized loss position for more than twelve months	8
Unrealized losses in loss position for twelve months or more	(12,181)			(1,806)
Number of individual securities with a continuous unrealized loss position less than 12 months	11
Unrealized losses in loss position for less than twelve months	(5,391)			(1,538)
Continuous unrealized loss position 12 months or more, fair value	182,697			79,442
Corporate debt securities | Non-investment grade
Schedule of Available-for-sale Securities
Fair value of available for sale securities	17,417	[1]		15,101	[1]
Unrealized losses in loss position for twelve months or more	(7,558)			(5,629)
Continuous unrealized loss position 12 months or more, fair value	12,574			14,422
Percentage of total amortized cost basis of these securities				28.00%
U.S. Treasury securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	460,677			491,632
Number of individual securities with a continuous unrealized loss position less than 12 months	9
Unrealized losses in loss position for less than twelve months	(71)			(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	180,665			178,870
Unrealized losses in loss position for twelve months or more				(1,169)
Number of individual securities with a continuous unrealized loss position less than 12 months	1
Unrealized losses in loss position for less than twelve months	(36)			(3,280)
Continuous unrealized loss position 12 months or more, fair value				$ 16,065

[1] For 2013, the Company did not record any OTTI. For 2012, the Company recorded $99 thousand, on a pre-tax basis, of the credit portion of OTTI through earnings and $5.1 million of the non-credit portion of OTTI for pooled trust preferred securities in other comprehensive income.