Commitments and Contingent Liabilities - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Customers' letters of credit	$ 8,600	$ 10,100
Reserve for unfunded loan commitments and letters of credit	848	611
Recourse reserves for loans	$ 1,900	$ 1,600

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant