Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Additional Information (Detail)

v3.8.0.1
Fair Value Measurements - Additional Information (Detail) - USD ($)
Sep. 30, 2017
Jun. 30, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Loans held for sale $ 6,469,000 $ 10,949,000 $ 9,316,000 $ 6,425,000 $ 12,833,000 $ 2,874,000
Minimum [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Unpaid principal balance of Non-accrual Non-PCI loans reviewed individually for amount of impairment 100,000          
Maximum [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Unpaid principal balance of Non-accrual Non-PCI loans reviewed collectively for amount of impairment 100,000          
Fair Value, Inputs, Level 2 [Member] | Non-recurring Basis [Member] | Non-Performing Loans Held for Sale [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Loans held for sale $ 0   $ 0