Loans Receivable and Allowance for Loan Losses - Summary of Loans Receivable by Credit Quality Risk Rating Indicator (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	$ 4,088,434	$ 3,686,862
Total loans	5,907,687	5,196,663
Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	1,223,145	1,174,043
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	1,669,614	1,400,624
Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	968,242	928,906
Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	227,433	183,289
Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	4,088,434	3,686,862
Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,201,741	932,199
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	617,512	577,602
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	86,148	50,951
Special Mention [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	4,572	5,062
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	10,643	15,301
Special Mention [Member] | Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	328	0
Special Mention [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	2,600	0
Special Mention [Member] | Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	18,143	20,363
Special Mention [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	66,372	28,551
Special Mention [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,633	2,037
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	123,418	137,362
Substandard [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	21,323	23,011
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	53,797	54,592
Substandard [Member] | Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	1,243	403
Substandard [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	8,449
Substandard [Member] | Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	76,363	86,455
Substandard [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	43,618	46,687
Substandard [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	3,437	4,220
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,144	649
Doubtful [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Doubtful [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Doubtful [Member] | Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Doubtful [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Doubtful [Member] | Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Doubtful [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,144	649
Doubtful [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loss [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Loss [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Loss [Member] | Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Loss [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Loss [Member] | Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	0	0
Loss [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loss [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Total classified and criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	210,710	188,962
Total classified and criticized [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	25,895	28,073
Total classified and criticized [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	64,440	69,893
Total classified and criticized [Member] | Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	1,571	403
Total classified and criticized [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	2,600	8,449
Total classified and criticized [Member] | Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	94,506	106,818
Total classified and criticized [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	111,134	75,887
Total classified and criticized [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	5,070	6,257
Pass/Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	5,696,977	5,007,701
Pass/Watch [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	1,197,250	1,145,970
Pass/Watch [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	1,605,174	1,330,731
Pass/Watch [Member] | Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	966,671	928,503
Pass/Watch [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	224,833	174,840
Pass/Watch [Member] | Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total mortgage loans	3,993,928	3,580,044
Pass/Watch [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,090,607	856,312
Pass/Watch [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 612,442	$ 571,345