Loans and Allowance for Loan Losses - Summary of Nonperforming and Restructured Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Summary Of Nonperforming And Restructured Assets [Abstract]
Past due 90 days or more and still accruing	$ 1,906	$ 1,841
Nonaccrual	31,014	30,096
Restructured	1,842	15,143
Total nonperforming and restructured loans	34,762	47,080
Other real estate owned and repossessed assets	4,339	8,214
Total nonperforming and restructured assets	$ 39,101	$ 55,294