COMMITMENTS AND CONTINGENCIES (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Undisbursed Loan Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contractual amount of liability	$ 2,190.0	$ 1,890.0
Commercial and Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contractual amount of liability	1,700.0	768.8
Loans Sold or Securitized with Recourse [Member]
Loss Contingencies [Line Items]
Principal amount of loans sold or securitized	620.2	699.6
Recourse reserve related to loan sales and securitizations totaled	4.3	4.7
Loans Sold or Securitized with Recourse [Member] | Single-family Loans with Full Recourse [Member]
Loss Contingencies [Line Items]
Principal amount of loans sold or securitized	55.9	60.9
Loans Sold or Securitized with Recourse [Member] | Multi-family Loans with Limited Recourse [Member]
Loss Contingencies [Line Items]
Principal amount of loans sold or securitized	564.3	638.7
Recourse provision limitation, maximum percentage of the top loss on the underlying loans (in hundredths)	4.00%	4.00%
Loans Sold without Recourse [Member]
Loss Contingencies [Line Items]
Principal amount of loans sold or securitized	1,280.0	1,480.0
Loans Securitized without Recourse [Member]
Loss Contingencies [Line Items]
Principal amount of loans sold or securitized	$ 291.6	$ 325.5