Balance and Interest Income Related to Impaired Loan Pools (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Financing Receivable, Recorded Investment [Line Items]
Interest income recognized	$ 176	$ 218	$ 386	$ 431
PCI loans
Financing Receivable, Recorded Investment [Line Items]
Interest income recognized	35	87	118	177
TDRs | PCI loans
Financing Receivable, Recorded Investment [Line Items]
Interest income recognized	$ 75	$ 160	$ 153	$ 308