FAIR VALUE (Details 7) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financial Liabilities
Other borrowings		$ 20,000
Estimated Fair Value
Financial Assets
Cash and cash equivalents	1,736,865	1,323,106
Short-term investments	379,029	366,378
Securities purchased under resale agreements	1,392,927	1,442,302
Loans held for sale	233,843	180,349
Loans receivable, net	14,818,860	14,743,218
Investment in Federal Home Loan Bank stock	96,795	107,275
Investment in Federal Reserve Bank stock	48,036	48,003
Accrued interest receivable	103,392	94,837
Financial Liabilities
Demand, savings and money market deposits	12,901,076	12,187,740
Time deposits	6,016,426	6,115,530
Federal Home Loan Bank advances	326,527	333,060
Securities sold under repurchase agreements	1,174,984	1,173,830
Other borrowings		20,000
Accrued interest payable	11,103	10,855
Long-term debt	88,379	83,762
Level 1
Financial Assets
Cash and cash equivalents	1,736,865	1,323,106
Level 2
Financial Assets
Short-term investments	379,029	366,378
Securities purchased under resale agreements	1,392,927	1,442,302
Loans held for sale	233,843	180,349
Investment in Federal Home Loan Bank stock	96,795	107,275
Investment in Federal Reserve Bank stock	48,036	48,003
Accrued interest receivable	103,392	94,837
Financial Liabilities
Demand, savings and money market deposits	12,901,076	12,187,740
Federal Home Loan Bank advances	326,527	333,060
Securities sold under repurchase agreements	1,174,984	1,173,830
Other borrowings		20,000
Accrued interest payable	11,103	10,855
Long-term debt	88,379	83,762
Level 3
Financial Assets
Loans receivable, net	14,818,860	14,743,218
Financial Liabilities
Time deposits	$ 6,016,426	$ 6,115,530