FAIR VALUE MEASUREMENT AND FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Investment securities available-for-sale
Total investment securities available-for-sale	$ 2,626,365		$ 2,733,797
U.S. Treasury securities
Investment securities available-for-sale
Total investment securities available-for-sale	873,435		491,632
U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Total investment securities available-for-sale	311,024		394,323
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Investment securities available-for-sale
Total investment securities available-for-sale	141,420		178,870
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Investment securities available-for-sale
Total investment securities available-for-sale	791,088		885,237
Municipal securities
Investment securities available-for-sale
Total investment securities available-for-sale	250,448		280,979
Other residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	53,918	[1]	46,327	[1]
Other commercial mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	34,053	[1]	51,617	[1]
Corporate debt securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	115,182	[1]	309,995	[1]
Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	14,681	[1]	15,101	[1]
Other securities
Investment securities available-for-sale
Total investment securities available-for-sale	41,116		79,716
Fair Value, Measurements, Recurring | Fair Value Measurements
Investment securities available-for-sale
Total investment securities available-for-sale	2,626,365		2,733,797
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign exchange options
Derivative
Derivative assets	6,136		6,290
Fair Value, Measurements, Recurring | Fair Value Measurements | Interest rate swaps and caps
Derivative
Derivative assets	41,534		28,078
Derivative liabilities	(41,779)		(26,352)
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign exchange contracts
Derivative
Derivative assets	8,123		6,181
Derivative liabilities	(9,171)		(3,349)
Fair Value, Measurements, Recurring | Fair Value Measurements | Interest rate swaps on certificates of deposits
Derivative
Derivative liabilities	(9,922)		(16,906)
Fair Value, Measurements, Recurring | Fair Value Measurements | Embedded derivatives liabilities
Derivative
Derivative liabilities	(3,392)		(3,655)
Fair Value, Measurements, Recurring | Fair Value Measurements | U.S. Treasury securities
Investment securities available-for-sale
Total investment securities available-for-sale	873,435		491,632
Fair Value, Measurements, Recurring | Fair Value Measurements | U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Total investment securities available-for-sale	311,024		394,323
Fair Value, Measurements, Recurring | Fair Value Measurements | U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Investment securities available-for-sale
Total investment securities available-for-sale	141,420		178,870
Fair Value, Measurements, Recurring | Fair Value Measurements | U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Investment securities available-for-sale
Total investment securities available-for-sale	791,088		885,237
Fair Value, Measurements, Recurring | Fair Value Measurements | Municipal securities
Investment securities available-for-sale
Total investment securities available-for-sale	250,448		280,979
Fair Value, Measurements, Recurring | Fair Value Measurements | Other residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	53,918		46,327
Fair Value, Measurements, Recurring | Fair Value Measurements | Other commercial mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	34,053		51,617
Fair Value, Measurements, Recurring | Fair Value Measurements | Corporate debt securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	115,182		309,995
Fair Value, Measurements, Recurring | Fair Value Measurements | Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	14,681		15,101
Fair Value, Measurements, Recurring | Fair Value Measurements | Other securities
Investment securities available-for-sale
Total investment securities available-for-sale	41,116		79,716
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment securities available-for-sale
Total investment securities available-for-sale	905,540		491,632
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities
Investment securities available-for-sale
Total investment securities available-for-sale	873,435		491,632
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other securities
Investment securities available-for-sale
Total investment securities available-for-sale	32,105
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Investment securities available-for-sale
Total investment securities available-for-sale	1,714,297		2,235,794
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange options
Derivative
Derivative assets	6,136		6,290
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps and caps
Derivative
Derivative assets	41,534		28,078
Derivative liabilities	(41,779)		(26,352)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Derivative
Derivative assets	8,123		6,181
Derivative liabilities	(9,171)		(3,349)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps on certificates of deposits
Derivative
Derivative liabilities	(9,922)		(16,906)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Total investment securities available-for-sale	311,024		394,323
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Investment securities available-for-sale
Total investment securities available-for-sale	141,420		178,870
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Investment securities available-for-sale
Total investment securities available-for-sale	791,088		885,237
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Municipal securities
Investment securities available-for-sale
Total investment securities available-for-sale	250,448		280,979
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	53,918		46,327
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other commercial mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	34,053		51,617
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	115,182		309,995
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	8,153		8,730
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other securities
Investment securities available-for-sale
Total investment securities available-for-sale	9,011		79,716
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Investment securities available-for-sale
Total investment securities available-for-sale	6,528		6,371
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Embedded derivatives liabilities
Derivative
Derivative liabilities	(3,392)		(3,655)
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	$ 6,528		$ 6,371

[1] Investment securities rated BBB- or higher by S&P, or Baa3 or higher by Moody are considered investment grade. Conversely, investment securities rated below BBB- by S&P, or below Baa3 by Moody are considered non-investment grade.