Loans - Loans by Class Modified as Troubled Debt Restructuring (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 SecurityLoan	Jun. 30, 2012 SecurityLoan	Jun. 30, 2013 SecurityLoan	Jun. 30, 2012 SecurityLoan
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	51	27	94	74
Pre-Modification Outstanding Recorded Investment	$ 8,338	$ 1,300	$ 10,743	$ 7,251
Post- Modification Recorded Investment	4,324	1,263	6,767	7,154
Permanent Real Estate Loans [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	13	7	26	28
Pre-Modification Outstanding Recorded Investment	5,522	350	6,265	4,169
Post- Modification Recorded Investment	1,841	345	2,603	4,126
Permanent Real Estate Loans [Member] | One-to Four-Family Residential [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	9	7	22	21
Pre-Modification Outstanding Recorded Investment	1,099	350	1,842	2,306
Post- Modification Recorded Investment	844	345	1,606	2,264
Permanent Real Estate Loans [Member] | Multi-Family Residential [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	1		1	6
Pre-Modification Outstanding Recorded Investment	469		469	1,439
Post- Modification Recorded Investment	469		469	1,438
Permanent Real Estate Loans [Member] | Nonresidential [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	1		1	1
Pre-Modification Outstanding Recorded Investment	41		41	424
Post- Modification Recorded Investment	41		41	424
Permanent Real Estate Loans [Member] | Land [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	2		2
Pre-Modification Outstanding Recorded Investment	3,913		3,913
Post- Modification Recorded Investment	487		487
Construction Loans [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	1		1	3
Pre-Modification Outstanding Recorded Investment	1,161		1,161	853
Post- Modification Recorded Investment	823		823	830
Construction Loans [Member] | One-to Four-Family Residential [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	1		1	3
Pre-Modification Outstanding Recorded Investment	1,161		1,161	853
Post- Modification Recorded Investment	823		823	830
Construction Loans [Member] | Multi-Family and Nonresidential [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans
Pre-Modification Outstanding Recorded Investment
Post- Modification Recorded Investment
Consumer Loans [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	37	20	67	42
Pre-Modification Outstanding Recorded Investment	1,655	950	3,317	1,783
Post- Modification Recorded Investment	1,660	918	3,341	1,752
Consumer Loans [Member] | Home Equity [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans	37	20	63	42
Pre-Modification Outstanding Recorded Investment	1,655	950	2,526	1,783
Post- Modification Recorded Investment	1,660	918	2,537	1,752
Consumer Loans [Member] | Auto [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans
Pre-Modification Outstanding Recorded Investment
Post- Modification Recorded Investment
Consumer Loans [Member] | Marine [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans
Pre-Modification Outstanding Recorded Investment
Post- Modification Recorded Investment
Consumer Loans [Member] | Recreational Vehicles [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans			4
Pre-Modification Outstanding Recorded Investment			791
Post- Modification Recorded Investment			804
Consumer Loans [Member] | Others [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans
Pre-Modification Outstanding Recorded Investment
Post- Modification Recorded Investment
Commercial Loans [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans				1
Pre-Modification Outstanding Recorded Investment				446
Post- Modification Recorded Investment				446
Commercial Loans [Member] | Secured [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans
Pre-Modification Outstanding Recorded Investment
Post- Modification Recorded Investment
Commercial Loans [Member] | Unsecured [Member]
Financing Receivable Modifications Number Of Contracts [Line Items]
Number of Loans				1
Pre-Modification Outstanding Recorded Investment				446
Post- Modification Recorded Investment				$ 446