Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail)

v3.8.0.1
Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Financial assets:    
Cash and due from banks $ 138,139 $ 147,235
Securities available for sale 598,440 516,964
Accrued interest receivable 12,098 10,987
Financial liabilities:    
Noninterest-bearing deposits 1,293,538 1,203,240
Interest-bearing deposits 3,005,472 2,606,497
Accrued interest payable 4,071 2,567
Carrying Amount [Member]    
Financial assets:    
Cash and due from banks 138,139 147,235
Securities available for sale 598,440 516,964
Loans and leases receivable, net of allowance for loan and lease losses 4,162,863 3,812,340
Loans held for sale 6,469 9,316
Accrued interest receivable 12,098 10,987
FHLB stock 16,385 16,385
Financial liabilities:    
Noninterest-bearing deposits 1,293,538 1,203,240
Interest-bearing deposits 3,005,472 2,606,497
Borrowings 227,140 333,978
Accrued interest payable 4,071 2,567
Off-balance sheet items:    
Commitments to extend credit 301,049 310,987
Carrying Amount [Member] | Standby letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 19,521 15,669
Carrying Amount [Member] | Commercial letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 6,833 4,215
Fair Value, Inputs, Level 1 [Member] | Fair Value [Member]    
Financial assets:    
Cash and due from banks 138,139 147,235
Securities available for sale   22,550
Loans and leases receivable, net of allowance for loan and lease losses 0 0
Loans held for sale 0 0
Accrued interest receivable 12,098 10,987
FHLB stock 0 0
Financial liabilities:    
Noninterest-bearing deposits 0 0
Interest-bearing deposits 0 0
Borrowings 0 0
Accrued interest payable 4,071 2,567
Off-balance sheet items:    
Commitments to extend credit 0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value [Member] | Standby letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value [Member] | Commercial letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value [Member]    
Financial assets:    
Cash and due from banks 0 0
Securities available for sale   494,414
Loans and leases receivable, net of allowance for loan and lease losses 0 0
Loans held for sale 6,469 9,316
Accrued interest receivable 0 0
FHLB stock 16,385 16,385
Financial liabilities:    
Noninterest-bearing deposits 1,293,538 1,203,240
Interest-bearing deposits 0 0
Borrowings 0 0
Accrued interest payable 0 0
Off-balance sheet items:    
Commitments to extend credit 0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value [Member] | Standby letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value [Member] | Commercial letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value [Member]    
Financial assets:    
Cash and due from banks 0 0
Securities available for sale   0
Loans and leases receivable, net of allowance for loan and lease losses 4,124,666 3,789,579
Loans held for sale 0 0
Accrued interest receivable 0 0
FHLB stock 0 0
Financial liabilities:    
Noninterest-bearing deposits 0 0
Interest-bearing deposits 2,956,667 2,541,929
Borrowings 227,140 333,978
Accrued interest payable 0 0
Off-balance sheet items:    
Commitments to extend credit 301,049 310,987
Fair Value, Inputs, Level 3 [Member] | Fair Value [Member] | Standby letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 19,521 15,669
Fair Value, Inputs, Level 3 [Member] | Fair Value [Member] | Commercial letters of credit [Member]    
Off-balance sheet items:    
Letters of credit $ 6,833 $ 4,215