NON-COVERED LOANS AND ALLOWANCE FOR LOAN LOSSES (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Non-Covered loans receivable disclosures
Accrued interest on covered and non-covered loans receivable	$ 76,800,000	$ 68,500,000
Covered and non-covered loans receivable pledged to secure borrowings from the FHLB and the Federal Reserve Bank	8,880,000,000	8,650,000,000
Residential
Non-Covered loans receivable disclosures
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
New first mortgage loans originated	735,300,000	924,300,000
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
New first mortgage loans originated	$ 128,400,000	$ 80,500,000
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