Outstanding Principal Balance and Related Carrying Amount of Credit-Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Outstanding principal balance	$ 15,975		$ 19,527
Carrying amount	$ 10,622	[1]	$ 12,128	[1]

[1] Includes $149 thousand and $319 thousand of purchased credit-impaired loans as of September 30, 2013 and December 31, 2012, respectively, for which the Bank could not estimate the timing or amount of expected cash flows to be collected at acquisition, and for which no accretable yield is recognized. Additionally, the table above includes $90 thousand of purchased credit-impaired loans as of both September 30, 2013 and December 31, 2012, which subsequently became non-performing, which are disclosed in Note 5C, above, and which also have no accretable yield.