Annual report pursuant to Section 13 and 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
Dec. 31, 2017
Dec. 31, 2016
Financial assets:    
Cash and due from banks $ 153,826 $ 147,235
Securities available for sale 578,804 516,964
Accrued interest receivable 12,770 10,987
Financial liabilities:    
Noninterest-bearing deposits 1,312,274 1,203,240
Interest-bearing deposits 3,036,380 2,606,497
Accrued interest payable 5,309 2,567
U.S. government agency securities [Member]    
Financial assets:    
Securities available for sale 7,414 7,441
Other securities [Member]    
Financial assets:    
Securities available for sale 22,386 22,394
Carrying Amount [Member]    
Financial assets:    
Cash and due from banks 153,826 147,235
Securities available for sale 578,804 516,964
Loans and leases receivable, net of allowance for loan and lease losses 4,273,415 3,812,340
Loans held for sale 6,394 9,316
Accrued interest receivable 12,770 10,987
FHLB stock 16,385 16,385
Financial liabilities:    
Noninterest-bearing deposits 1,312,274 1,203,240
Interest-bearing deposits 3,036,380 2,606,497
Borrowings 267,270 333,978
Accrued interest payable 5,309 2,567
Off-balance sheet items:    
Commitments to extend credit 318,634 310,987
Standby letters of credit 19,294 15,669
Commercial letters of credit 9,308 4,215
Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets [Member]    
Financial assets:    
Cash and due from banks 153,826 147,235
Securities available for sale 22,538 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 12,770 10,987
FHLB stock 0 0
Financial liabilities:    
Noninterest-bearing deposits 0 0
Interest-bearing deposits 0 0
Borrowings 0 0
Accrued interest payable 5,309 2,567
Off-balance sheet items:    
Commitments to extend credit 0 0
Standby letters of credit 0 0
Commercial letters of credit 0 0
Fair Value [Member] | Significant Observable Inputs with No Active Market with Identical Characteristics [Member]    
Financial assets:    
Cash and due from banks 0 0
Securities available for sale 556,266 494,414
Loans and leases receivable, net of allowance for loan and lease losses 0 0
Loans held for sale 6,394 9,316
Accrued interest receivable 0 0
FHLB stock 16,385 16,385
Financial liabilities:    
Noninterest-bearing deposits 1,312,274 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
Standby letters of credit 0 0
Commercial letters of credit 0 0
Fair Value [Member] | Significant Unobservable Inputs [Member]    
Financial assets:    
Cash and due from banks 0 0
Securities available for sale 0 0
Loans and leases receivable, net of allowance for loan and lease losses 4,213,689 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 2,973,139 2,541,929
Borrowings 267,270 333,978
Accrued interest payable 0 0
Off-balance sheet items:    
Commitments to extend credit 318,634 310,987
Standby letters of credit 19,294 15,669
Commercial letters of credit $ 9,308 $ 4,215