NON-COVERED LOANS AND ALLOWANCE FOR LOAN LOSSES (Details) (USD $)	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	$ 10,794,870,000		$ 10,288,426,000
Unearned fees, premiums and discounts, net	(19,762,000)		(16,762,000)
Allowance for non-covered loans receivable	(219,454,000)		(209,876,000)
Non-covered loans receivable, excluding covered loans, net	10,555,654,000		10,061,788,000
Accrued interest on covered and non-covered loans receivable	70,200,000		68,500,000
Covered and non-covered loans receivable pledged to secure borrowings from the FHLB and the Federal Reserve Bank	8,830,000,000		8,650,000,000
Residential
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	2,930,818,000		2,729,803,000
Ratio of mortgage loans with variable payment option features to total mortgage loans within same portfolio category (as a percent)	1.00%		1.00%
Residential | Minimum
Non-Covered loans receivable disclosures
Number of units of residential property securing fixed and adjustable rate first mortgage loans	1
Residential | Maximum
Non-Covered loans receivable disclosures
Number of units of residential property securing fixed and adjustable rate first mortgage loans	4
Residential | Single-family
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	2,017,877,000		1,796,635,000
New first mortgage loans originated	369,700,000	294,700,000
Loans to value ratio (as a percent)	65.00%
Ratio of mortgage loans with interest-only features to total mortgage loans within same portfolio category (as a percent)	1.00%		1.00%
Residential | Multifamily
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	912,941,000		933,168,000
New first mortgage loans originated	52,700,000	23,900,000
Residential | Multifamily | Minimum
Non-Covered loans receivable disclosures
Adjustable rate mortgage, term of initial fixed interest rates	6 months
Residential | Multifamily | Midrange
Non-Covered loans receivable disclosures
Adjustable rate mortgage, term of initial fixed interest rates	3 years
Residential | Multifamily | Maximum
Non-Covered loans receivable disclosures
Adjustable rate mortgage, term of initial fixed interest rates	5 years
Commercial Real Estate ("CRE")
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	3,744,696,000		3,832,365,000
Commercial Real Estate ("CRE") | Income producing
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	3,444,957,000		3,487,866,000
Commercial Real Estate ("CRE") | Construction
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	134,621,000		171,410,000
Commercial Real Estate ("CRE") | Land
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	165,118,000		173,089,000
Commercial and Industrial ("C&I")
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	3,418,637,000		3,142,472,000
Commercial and Industrial ("C&I") | Commercial Business
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	2,860,172,000		2,655,917,000
Commercial and Industrial ("C&I") | Trade finance
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	558,465,000		486,555,000
Consumer
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	700,719,000		583,786,000
Consumer | Student loans
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	436,527,000		306,325,000
Consumer | Other Consumer
Non-Covered loans receivable disclosures
Loans receivable, excluding covered loans, gross	$ 264,192,000		$ 277,461,000