FAIR VALUE MEASUREMENT AND FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Investment securities available-for-sale
Total investment securities available-for-sale	$ 2,592,667		$ 2,733,797
U.S. Treasury securities
Investment securities available-for-sale
Total investment securities available-for-sale	603,647		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	412,981		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	125,567		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	757,582		885,237
Municipal securities
Investment securities available-for-sale
Total investment securities available-for-sale	296,597		280,979
Other residential mortgage-backed securities: | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	55,258	[1]	46,327	[1]
Other commercial mortgage-backed securities: | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	51,127	[1]	51,617	[1]
Corporate debt securities | Investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	210,825	[1]	309,995	[1]
Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Total investment securities available-for-sale	17,776	[1]	15,101	[1]
Other securities
Investment securities available-for-sale
Total investment securities available-for-sale	61,307		79,716
Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment securities available-for-sale
Total investment securities available-for-sale	603,647		491,632
Significant Other Observable Inputs (Level 2)
Investment securities available-for-sale
Total investment securities available-for-sale	1,980,111		2,235,794
Derivative
Derivatives liabilities	(50,660)		(46,607)
Significant Other Observable Inputs (Level 2) | Foreign exchange options
Derivative
Derivative assets	6,155		6,290
Significant Other Observable Inputs (Level 2) | Interest rate swaps and caps
Derivative
Derivative assets	29,170		28,078
Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Derivative
Derivative assets	9,204		6,181
Significant Unobservable Inputs (Level 3)
Investment securities available-for-sale
Total investment securities available-for-sale	8,909		6,371
Derivative
Derivatives liabilities	(3,426)		(3,655)
Fair Value, Measurements, Recurring | Fair Value Measurements
Investment securities available-for-sale
Total investment securities available-for-sale	2,592,667		2,733,797
Derivative
Derivatives liabilities	(54,086)		(50,262)
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign exchange options
Derivative
Derivative assets	6,155		6,290
Fair Value, Measurements, Recurring | Fair Value Measurements | Interest rate swaps and caps
Derivative
Derivative assets	29,170		28,078
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign exchange contracts
Derivative
Foreign exchange contracts	9,204		6,181
Fair Value, Measurements, Recurring | Fair Value Measurements | U.S. Treasury securities
Investment securities available-for-sale
Total investment securities available-for-sale	603,647		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	412,981		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	125,567		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	757,582		885,237
Fair Value, Measurements, Recurring | Fair Value Measurements | Municipal securities
Investment securities available-for-sale
Total investment securities available-for-sale	296,597		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	55,258		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	51,127		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	210,825		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	17,776		15,101
Fair Value, Measurements, Recurring | Fair Value Measurements | Other securities
Investment securities available-for-sale
Total investment securities available-for-sale	61,307		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	603,647		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	603,647		491,632
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Investment securities available-for-sale
Total investment securities available-for-sale	1,980,111		2,235,794
Derivative
Derivatives liabilities	(50,660)		(46,607)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange options
Derivative
Derivative assets	6,155		6,290
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps and caps
Derivative
Derivative assets	29,170		28,078
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Derivative
Foreign exchange contracts	9,204		6,181
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	412,981		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	125,567		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	757,582		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	296,597		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	55,258		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	51,127		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	210,825		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	8,867		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	61,307		79,716
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Investment securities available-for-sale
Total investment securities available-for-sale	8,909		6,371
Derivative
Derivatives liabilities	(3,426)		(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	$ 8,909		$ 6,371

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