Reserve for Repurchased Loans and Loss Sharing Obligations - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013 SecurityLoan	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012 SecurityLoan	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2011
Loans Receivable [Line Items]
Reserve for repurchased loans and loss sharing obligations	$ 1,688,000	$ 955,000	$ 1,688,000	$ 955,000	$ 1,203,000	$ 1,688,000	$ 855,000	$ 705,000
Increase in reserve for repurchased loans and loss sharing obligations			485,000
General provision for repurchased loans		100,000	975,000	250,000
Additional provision for covered losses			875,000
Maximum remaining loss exposure on all loans sold to FHLB	1,900,000		1,900,000
Reserve reduced by cash paid as part of settlement			450,000
Loan repurchase request, outstanding	5				12
Recognized recoveries			205,000
Total principal balance	1,100,000		1,100,000		3,600,000
Settlement of Loan [Member]
Loans Receivable [Line Items]
Loan repurchase request, outstanding			7
Repurchase Requests [Member]
Loans Receivable [Line Items]
General provision for repurchased loans			100,000
MPF Program [Member]
Loans Receivable [Line Items]
Recognized losses on loans			$ 245,000
Loans Sold To FHLB Under Loss Sharing Arrangement [Member]
Loans Receivable [Line Items]
Loans sold to FHLB under loss sharing arrangement first loss position			1.00%
Loans sold to FHLB under loss sharing arrangement minimum exposure			1.50%
Loans sold to FHLB under loss sharing arrangement maximum loss position			4.00%