Guarantees, Commitments and Contingencies - Summary of Commitments and Contingent Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Summary Of Commitments And Contingent Liabilities [Line Items]
Commitments and contingent liabilities
Standby Letters of Credit [Member]
Summary Of Commitments And Contingent Liabilities [Line Items]
Commitments and contingent liabilities	$ 683	$ 833
Commitments to Extend Credit [Member]
Summary Of Commitments And Contingent Liabilities [Line Items]
Commitments and contingent liabilities	$ 29,914	$ 31,644