Loans Receivable and Allowance for Loan Losses - Summary of Impaired Loans Receivable by Class (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$ 94,514	$ 116,056
Recorded Investment	85,395	106,370
Related Allowance	7,127	10,217
Average Recorded Investment	87,869	111,008
Interest Income Recognized	2,328	2,598
Residential [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	30,465	30,581
Recorded Investment	25,535	26,472
Related Allowance	2,367	2,571
Average Recorded Investment	26,244	26,932
Interest Income Recognized	912	856
Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	42,526	42,237
Recorded Investment	41,014	40,918
Related Allowance	2,329	2,309
Average Recorded Investment	41,387	41,561
Interest Income Recognized	914	979
Multi-Family [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	0	9,810
Recorded Investment	0	8,449
Related Allowance	0	2,949
Average Recorded Investment	0	8,659
Interest Income Recognized	0	0
Mortgage Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	72,991	82,628
Recorded Investment	66,549	75,839
Related Allowance	4,696	7,829
Average Recorded Investment	67,631	77,152
Interest Income Recognized	1,826	1,835
Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	18,708	30,942
Recorded Investment	16,462	28,210
Related Allowance	2,318	2,221
Average Recorded Investment	17,790	31,456
Interest Income Recognized	394	674
Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	2,815	2,486
Recorded Investment	2,384	2,321
Related Allowance	113	167
Average Recorded Investment	2,448	2,400
Interest Income Recognized	108	89
Loans With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	23,881	27,293
Recorded Investment	18,346	21,958
Related Allowance	0	0
Average Recorded Investment	18,544	24,082
Interest Income Recognized	389	352
Loans With No Related Allowance [Member] | Residential [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	14,942	13,459
Recorded Investment	10,629	9,999
Related Allowance	0	0
Average Recorded Investment	11,138	10,322
Interest Income Recognized	357	299
Loans With No Related Allowance [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	4,971	4,917
Recorded Investment	4,708	4,667
Related Allowance	0	0
Average Recorded Investment	4,713	4,834
Interest Income Recognized	0	3
Loans With No Related Allowance [Member] | Multi-Family [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Loans With No Related Allowance [Member] | Construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Loans With No Related Allowance [Member] | Mortgage Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	19,913	18,376
Recorded Investment	15,337	14,666
Related Allowance	0	0
Average Recorded Investment	15,851	15,156
Interest Income Recognized	357	302
Loans With No Related Allowance [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	2,718	8,163
Recorded Investment	2,179	6,674
Related Allowance	0	0
Average Recorded Investment	1,823	8,252
Interest Income Recognized	4	24
Loans With No Related Allowance [Member] | Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	1,250	754
Recorded Investment	830	618
Related Allowance	0	0
Average Recorded Investment	870	674
Interest Income Recognized	28	26
Loans With Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	70,633	88,763
Recorded Investment	67,049	84,412
Related Allowance	7,127	10,217
Average Recorded Investment	69,325	86,926
Interest Income Recognized	1,939	2,246
Loans With Allowance Recorded [Member] | Residential [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	15,523	17,122
Recorded Investment	14,906	16,473
Related Allowance	2,367	2,571
Average Recorded Investment	15,106	16,610
Interest Income Recognized	555	557
Loans With Allowance Recorded [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	37,555	37,320
Recorded Investment	36,306	36,251
Related Allowance	2,329	2,309
Average Recorded Investment	36,674	36,727
Interest Income Recognized	914	976
Loans With Allowance Recorded [Member] | Multi-Family [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Loans With Allowance Recorded [Member] | Construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	0	9,810
Recorded Investment	0	8,449
Related Allowance	0	2,949
Average Recorded Investment	0	8,659
Interest Income Recognized	0	0
Loans With Allowance Recorded [Member] | Mortgage Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	53,078	64,252
Recorded Investment	51,212	61,173
Related Allowance	4,696	7,829
Average Recorded Investment	51,780	61,996
Interest Income Recognized	1,469	1,533
Loans With Allowance Recorded [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	15,990	22,779
Recorded Investment	14,283	21,536
Related Allowance	2,318	2,221
Average Recorded Investment	15,967	23,204
Interest Income Recognized	390	650
Loans With Allowance Recorded [Member] | Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	1,565	1,732
Recorded Investment	1,554	1,703
Related Allowance	113	167
Average Recorded Investment	1,578	1,726
Interest Income Recognized	$ 80	$ 63