FAIR VALUE MEASUREMENT AND FAIR VALUE OF FINANCIAL INSTRUMENTS (Details 7) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Financial Assets:
Cash and cash equivalents	$ 1,115,753	$ 895,820	$ 1,322,383	$ 1,323,106
Short-term investments	336,419	257,473
Securities purchased under resale agreements	1,475,000	1,300,000
Investment securities available-for-sale	2,592,667	2,733,797
Loans held for sale	239,649	204,970
Loans receivable, net	20,733,516	17,600,613
Investment in Federal Home Loan Bank stock	34,691	62,330
Investment in Federal Reserve Bank stock	54,324	48,333
Accrued interest receivable	96,054	116,314
Financial Liabilities:
Federal Home Loan Bank advances	316,699	315,092
Securities sold under repurchase agreements	805,106	995,000
Long-term debt	230,790	226,868
Maximum term of maturity for securities purchased under resale agreements to be included in cash and cash equivalents	90 days
Term of maturity that securities purchased under resale agreements must exceed to be included in certain fair value calculations	90 days
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets:
Cash and cash equivalents	1,115,753	895,820
Investment securities available-for-sale	603,647	491,632
Significant Other Observable Inputs (Level 2)
Financial Assets:
Short-term investments	336,419	257,473
Securities purchased under resale agreements	1,443,390	1,279,406
Investment securities available-for-sale	1,980,111	2,235,794
Loans held for sale	258,512	212,469
Investment in Federal Home Loan Bank stock	34,691	62,330
Investment in Federal Reserve Bank stock	54,324	48,333
Accrued interest receivable	96,054	116,314
Financial Liabilities:
Demand, savings and money market deposits	17,676,394	14,588,570
Federal Home Loan Bank advances	333,681	308,521
Securities sold under repurchase agreements	879,564	1,134,774
Accrued interest payable	10,817	11,178
Long-term debt	201,209	184,415
Derivative liabilities	50,660	46,607
Significant Other Observable Inputs (Level 2) | Foreign exchange options
Financial Assets:
Derivative assets	6,155	6,290
Significant Other Observable Inputs (Level 2) | Interest rate swaps and caps
Financial Assets:
Derivative assets	29,170	28,078
Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Financial Assets:
Derivative assets	9,204	6,181
Significant Unobservable Inputs (Level 3)
Financial Assets:
Investment securities available-for-sale	8,909	6,371
Loans receivable, net	19,933,809	16,741,674
Financial Liabilities:
Time deposits	6,116,966	5,791,659
Derivative liabilities	3,426	3,655
Carrying Amount
Financial Assets:
Cash and cash equivalents	1,115,753	895,820
Short-term investments	336,419	257,473
Securities purchased under resale agreements	1,475,000	1,300,000
Investment securities available-for-sale	2,592,667	2,733,797
Loans held for sale	239,649	204,970
Loans receivable, net	20,733,516	17,600,613
Investment in Federal Home Loan Bank stock	34,691	62,330
Investment in Federal Reserve Bank stock	54,324	48,333
Accrued interest receivable	96,054	116,314
Financial Liabilities:
Demand, savings and money market deposits	17,676,394	14,588,570
Time deposits	6,135,870	5,824,348
Federal Home Loan Bank advances	316,699	315,092
Securities sold under repurchase agreements	805,106	995,000
Accrued interest payable	10,817	11,178
Long-term debt	230,790	226,868
Derivative liabilities	54,086	50,262
Carrying Amount | Foreign exchange options
Financial Assets:
Derivative assets	6,155	6,290
Carrying Amount | Interest rate swaps and caps
Financial Assets:
Derivative assets	29,170	28,078
Carrying Amount | Foreign exchange contracts
Financial Assets:
Derivative assets	9,204	6,181
Fair Value
Financial Assets:
Cash and cash equivalents	1,115,753	895,820
Short-term investments	336,419	257,473
Securities purchased under resale agreements	1,443,390	1,279,406
Investment securities available-for-sale	2,592,667	2,733,797
Loans held for sale	258,512	212,469
Loans receivable, net	19,933,809	16,741,674
Investment in Federal Home Loan Bank stock	34,691	62,330
Investment in Federal Reserve Bank stock	54,324	48,333
Accrued interest receivable	96,054	116,314
Financial Liabilities:
Demand, savings and money market deposits	17,676,394	14,588,570
Time deposits	6,116,966	5,791,659
Federal Home Loan Bank advances	333,681	308,521
Securities sold under repurchase agreements	879,564	1,134,774
Accrued interest payable	10,817	11,178
Long-term debt	201,209	184,415
Derivative liabilities	54,086	50,262
Fair Value | Foreign exchange options
Financial Assets:
Derivative assets	6,155	6,290
Fair Value | Interest rate swaps and caps
Financial Assets:
Derivative assets	29,170	28,078
Fair Value | Foreign exchange contracts
Financial Assets:
Derivative assets	$ 9,204	$ 6,181