ALLOWANCE FOR LOAN LOSSES AND RESERVE FOR FIRST LOSS POSITION ON MULTIFAMILY LOANS SOLD TO FNMA (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Dec. 31, 2012
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable Substandard Non-impaired loans period end balance	$ 697				$ 795
Increase (Decrease) in the balance of Substandard non-impaired loans	(2,099)
Financing Receivable Special Mention Allowance For Loan Losses period end balance	242				145
Reserve For First Loss Position [Abstract]
Outstanding balance of multifamily loans serviced for FNMA at period end	244,159		300,347
First Loss Position Loans Serviced For Fnma	15,428		16,356
Balance at beginning of period	1,383		2,993
Transfer of specific reserve for serviced loans re-acquired by the Bank	0		0
Credit for losses on problem loans(1)	(92)	[1]	0	[1]
Charge-offs and other net reductions in balance	0		(35)
Balance at period end	1,291		2,958
One To Four Family Residential And Cooperative Unit Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	344		480
Provision (credit) for loan losses	92		363
Charge-offs	(88)		(531)
Recoveries	2		1
Financing Receivable Allowance For Credit Losses Transfers			0
Ending balance	350		313
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Ending balance - loans individually evaluated for impairment	1,209				1,291
Ending balance - loans collectively evaluated for impairment	84,803				90,585
Allowance balance associated with loans individually evaluated for impairment	7				7
Allowance balance associated with loans collectivelly evaluated for impairment	343				337
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,076				1,079
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	257				258
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	998	[2]			1,079	[2]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	211	[2]			212	[2]
Impaired Financing Receivables With No Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivables With Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	7				7
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,039		1,104
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	211		706
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	10		12
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	5		0
Multifamily Residential And Residential Mixed Use Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	14,299		14,313
Provision (credit) for loan losses	(298)		399
Charge-offs	(111)		(897)
Recoveries	0		23
Financing Receivable Allowance For Credit Losses Transfers			33
Ending balance	13,890		13,871
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Ending balance - loans individually evaluated for impairment	2,347				2,460
Ending balance - loans collectively evaluated for impairment	2,708,577				2,673,909
Allowance balance associated with loans individually evaluated for impairment	0				0
Allowance balance associated with loans collectivelly evaluated for impairment	13,890				14,299
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,347				2,767
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0				0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,347	[2]			2,460	[2]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[2]			0	[2]
Impaired Financing Receivables With No Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivables With Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,403		7,569
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0		1,050
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	48		131
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0		0
Mixed Use Commercial Real Estate Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,474		1,528
Provision (credit) for loan losses	87		1,251
Charge-offs	0		(526)
Recoveries	29		0
Financing Receivable Allowance For Credit Losses Transfers			(4)
Ending balance	2,590		2,249
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Ending balance - loans individually evaluated for impairment	1,882				1,900
Ending balance - loans collectively evaluated for impairment	339,175				338,233
Allowance balance associated with loans individually evaluated for impairment	0				0
Allowance balance associated with loans collectivelly evaluated for impairment	2,590				2,474
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,882				1,900
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0				0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,882	[2]			1,900	[2]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[2]			0	[2]
Impaired Financing Receivables With No Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivables With Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,891		3,880
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0		480
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	52		24
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0		0
Total Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	20,523		20,228
Provision (credit) for loan losses	152		1,451
Charge-offs	(203)		(2,280)
Recoveries	32		25
Financing Receivable Allowance For Credit Losses Transfers			20
Ending balance	20,504		19,444
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Ending balance - loans individually evaluated for impairment	49,177				53,144
Ending balance - loans collectively evaluated for impairment	3,495,210				3,450,241
Allowance balance associated with loans individually evaluated for impairment	490				520
Allowance balance associated with loans collectivelly evaluated for impairment	20,014				20,003
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	34,951				39,162
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	15,464				15,534
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	33,759	[2]			37,656	[2]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	15,418	[2]			15,488	[2]
Impaired Financing Receivables With No Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivables With Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	490				520
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	35,708		36,254
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	15,452		29,531
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	508		665
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	263		190
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	27		26
Provision (credit) for loan losses	5		6
Charge-offs	(6)		(8)
Recoveries	0		0
Financing Receivable Allowance For Credit Losses Transfers			0
Ending balance	26		24
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Ending balance - loans individually evaluated for impairment	0				0
Ending balance - loans collectively evaluated for impairment	1,967				2,423
Allowance balance associated with loans individually evaluated for impairment	0				0
Allowance balance associated with loans collectivelly evaluated for impairment	26				27
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	3,382		3,783
Provision (credit) for loan losses	273		(441)
Charge-offs	(4)		(323)
Recoveries	1		1
Financing Receivable Allowance For Credit Losses Transfers			(9)
Ending balance	3,652		3,011
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Ending balance - loans individually evaluated for impairment	43,739				47,493
Ending balance - loans collectively evaluated for impairment	362,239				347,038
Allowance balance associated with loans individually evaluated for impairment	483				513
Allowance balance associated with loans collectivelly evaluated for impairment	3,169				2,869
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	29,646				33,416
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	15,207				15,276
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	28,532	[2]			32,217	[2]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	15,207	[2]			15,276	[2]
Impaired Financing Receivables With No Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivables With Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	483				513
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	30,375		23,701
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	15,241		27,295
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	398		498
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	258		190
Construction Loan Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	24		124
Provision (credit) for loan losses	(2)		(121)
Charge-offs	0		(3)
Recoveries	0		0
Financing Receivable Allowance For Credit Losses Transfers			0
Ending balance	22		0
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Ending balance - loans individually evaluated for impairment	0				0
Ending balance - loans collectively evaluated for impairment	416				476
Allowance balance associated with loans individually evaluated for impairment	0				0
Allowance balance associated with loans collectivelly evaluated for impairment	22				24
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0				0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0				0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	[2]			0	[2]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[2]			0	[2]
Impaired Financing Receivables With No Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivables With Allocated Reserves Within Allowance For Loan Losses Recognized For Impaired Receivables	0				0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0		0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	0		0
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	$ 0		$ 0

[1] 1) Amount recognized as a component of mortgage banking income during the period.

[2] (1)The recorded investment excludes accrued interest receivable and loan origination fees, net, due to immateriality.