FAIR VALUE MEASUREMENT AND FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investment securities available-for-sale
Total available-for-sale investment securities	$ 3,205,238	$ 3,773,226
U.S. Treasury securities
Investment securities available-for-sale
Total available-for-sale investment securities	516,755	998,515
U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Total available-for-sale investment securities	788,935	768,849
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Investment securities available-for-sale
Total available-for-sale investment securities	326,987	351,662
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Investment securities available-for-sale
Total available-for-sale investment securities	935,099	997,396
Municipal securities
Investment securities available-for-sale
Total available-for-sale investment securities	159,426	175,649
Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	59,899	62,393
Corporate debt securities | Investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	365,905	364,713
Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	7,924	9,642
Other securities
Investment securities available-for-sale
Total available-for-sale investment securities	44,308	44,407
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment securities available-for-sale
Total available-for-sale investment securities	552,967	1,034,150
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities
Investment securities available-for-sale
Total available-for-sale investment securities	516,755	998,515
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other securities
Investment securities available-for-sale
Total available-for-sale investment securities	36,212	35,635
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Investment securities available-for-sale
Total available-for-sale investment securities	2,652,271	2,739,076
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps on certificates of deposit
Derivative
Derivative assets	54
Derivative liabilities	(1,038)	(5,213)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign currency forward contracts
Derivative
Derivative assets		2,365
Derivative liabilities	(430)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps and options
Derivative
Derivative assets	129,599	67,215
Derivative liabilities	(130,420)	(67,325)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Derivative
Derivative assets	8,817	10,254
Derivative liabilities	(6,196)	(9,350)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Credit risk participation agreements (“RPAs”)
Derivative
Derivative liabilities	(11)	(4)
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 available-for-sale investment securities	788,935	768,849
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 available-for-sale investment securities	326,987	351,662
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 available-for-sale investment securities	935,099	997,396
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Municipal securities
Investment securities available-for-sale
Total available-for-sale investment securities	159,426	175,649
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	59,899	62,393
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	365,905	364,713
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	7,924	9,642
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other securities
Investment securities available-for-sale
Total available-for-sale investment securities	8,096	8,772
Fair Value, Measurements, Recurring | Fair Value Measurements
Investment securities available-for-sale
Total available-for-sale investment securities	3,205,238	3,773,226
Fair Value, Measurements, Recurring | Fair Value Measurements | Interest rate swaps on certificates of deposit
Derivative
Derivative assets	54
Derivative liabilities	(1,038)	(5,213)
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign currency forward contracts
Derivative
Derivative assets		2,365
Derivative liabilities	(430)
Fair Value, Measurements, Recurring | Fair Value Measurements | Interest rate swaps and options
Derivative
Derivative assets	129,599	67,215
Derivative liabilities	(130,420)	(67,325)
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign exchange contracts
Derivative
Derivative assets	8,817	10,254
Derivative liabilities	(6,196)	(9,350)
Fair Value, Measurements, Recurring | Fair Value Measurements | Credit risk participation agreements (“RPAs”)
Derivative
Derivative liabilities	(11)	(4)
Fair Value, Measurements, Recurring | Fair Value Measurements | U.S. Treasury securities
Investment securities available-for-sale
Total available-for-sale investment securities	516,755	998,515
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 available-for-sale investment securities	788,935	768,849
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 available-for-sale investment securities	326,987	351,662
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 available-for-sale investment securities	935,099	997,396
Fair Value, Measurements, Recurring | Fair Value Measurements | Municipal securities
Investment securities available-for-sale
Total available-for-sale investment securities	159,426	175,649
Fair Value, Measurements, Recurring | Fair Value Measurements | Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	59,899	62,393
Fair Value, Measurements, Recurring | Fair Value Measurements | Corporate debt securities | Investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	365,905	364,713
Fair Value, Measurements, Recurring | Fair Value Measurements | Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Total available-for-sale investment securities	7,924	9,642
Fair Value, Measurements, Recurring | Fair Value Measurements | Other securities
Investment securities available-for-sale
Total available-for-sale investment securities	$ 44,308	$ 44,407