LOANS, Credit Quality Indicator (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Real estate loans not individually assigned a credit rating	$ 0		$ 0
One-to four Family Residential and Cooperative Unit [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	75,735		70,717
Real estate loans not individually assigned a credit rating	16,141	[1]	29,995	[1]
Multifamily Residential and Residential Mixed Use [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	2,676,369		2,602,919
Financing Receivable, Net	2,676,369		2,602,919
Mixed Use Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	340,133		338,270
Financing Receivable, Net	340,133		338,270
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	394,531		413,316
Construction Loan Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	476		3,199
Financing Receivable, Net	476		3,199
Total Real Estate Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	3,487,244		3,428,421
Real estate loans not individually assigned a credit rating	16,141		29,995
Financing Receivable, Net	3,503,385		3,458,416
Consumer Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,423		2,449
Pass [Member] | One-to four Family Residential and Cooperative Unit [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	66,415		66,949
Pass [Member] | Multifamily Residential and Residential Mixed Use [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	2,665,410		2,587,573
Pass [Member] | Mixed Use Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	326,053		320,556
Pass [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	363,299		364,462
Pass [Member] | Construction Loan Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	0		0
Pass [Member] | Total Real Estate Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	3,421,177		3,339,540
Special Mention [Member] | One-to four Family Residential and Cooperative Unit [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	6,333		1,133
Special Mention [Member] | Multifamily Residential and Residential Mixed Use [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	7,711		7,101
Special Mention [Member] | Mixed Use Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	5,547		10,562
Special Mention [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	2,639		9,244
Special Mention [Member] | Construction Loan Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	0		2,576
Special Mention [Member] | Total Real Estate Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	22,230		30,616
Substandard [Member] | One-to four Family Residential and Cooperative Unit [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	2,987		2,635
Substandard [Member] | Multifamily Residential and Residential Mixed Use [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	3,248		8,245
Substandard [Member] | Mixed Use Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	8,533		7,152
Substandard [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	28,593		39,610
Substandard [Member] | Construction Loan Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	476		623
Substandard [Member] | Total Real Estate Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total real estate loans individually assigned a credit rating	43,837		58,265
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Real estate loans not individually assigned a credit rating	2,423		2,449
Consumer Loans [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Real estate loans not individually assigned a credit rating	2,415		2,445
Consumer Loans [Member] | Non-accrual Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Real estate loans not individually assigned a credit rating	$ 8		$ 4

[1] (1) Amount comprised of fully performing one- to four-family residential and cooperative unit loans with balances equal to or less than the FNMA Limits. The credit quality of these loans was instead evaluated based upon payment activity.