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
Mar. 31, 2018
Dec. 31, 2017
Financial assets:    
Cash and due from banks $ 151,611 $ 153,826
Securities available for sale 570,351 578,804
Accrued interest receivable 12,751 12,770
Financial liabilities:    
Noninterest-bearing deposits 1,352,162 1,312,274
Interest-bearing deposits 3,025,939 3,036,380
Accrued interest payable 5,931 5,309
Carrying Amount [Member]    
Financial assets:    
Cash and due from banks 151,611 153,826
Securities available for sale 570,351 578,804
Loans and leases receivable, net of allowance for loan and lease losses 4,381,780 4,273,415
Loans held for sale 6,008 6,394
Accrued interest receivable 12,751 12,770
FHLB stock 16,385 16,385
Financial liabilities:    
Noninterest-bearing deposits 1,352,162 1,312,274
Interest-bearing deposits 3,025,939 3,036,380
Borrowings and subordinated debentures 337,400 267,270
Accrued interest payable 5,931 5,309
Off-balance sheet items:    
Commitments to extend credit 324,528 318,634
Carrying Amount [Member] | Standby letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 22,288 19,294
Carrying Amount [Member] | Commercial letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 11,560 9,308
Fair Value, Inputs, Level 1 [Member] | Fair Value [Member]    
Financial assets:    
Cash and due from banks 151,611 153,826
Securities available for sale   22,538
Loans and leases receivable, net of allowance for loan and lease losses 0 0
Loans held for sale 0 0
Accrued interest receivable 12,751 12,770
FHLB stock 0 0
Financial liabilities:    
Noninterest-bearing deposits 0 0
Interest-bearing deposits 0 0
Borrowings and subordinated debentures 0 0
Accrued interest payable 5,931 5,309
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   556,266
Loans and leases receivable, net of allowance for loan and lease losses 0 0
Loans held for sale 6,461 6,394
Accrued interest receivable 0 0
FHLB stock 16,385 16,385
Financial liabilities:    
Noninterest-bearing deposits 1,352,162 1,312,274
Interest-bearing deposits 0 0
Borrowings and subordinated debentures 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 4,392,889 4,213,689
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 2,905,169 2,973,139
Borrowings and subordinated debentures 337,822 267,270
Accrued interest payable 0 0
Off-balance sheet items:    
Commitments to extend credit 324,528 318,634
Fair Value, Inputs, Level 3 [Member] | Fair Value [Member] | Standby letters of credit [Member]    
Off-balance sheet items:    
Letters of credit 22,288 19,294
Fair Value, Inputs, Level 3 [Member] | Fair Value [Member] | Commercial letters of credit [Member]    
Off-balance sheet items:    
Letters of credit $ 11,560 $ 9,308