Loans and Allowance for Loan and Lease Losses - Loans on Nonaccrual Status by Portfolio Type (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
Nonaccrual loans	$ 21,784	$ 24,053
Commercial loans [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
Nonaccrual loans	14,238	16,182
Commercial real estate [Member] | Owner occupied [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
Nonaccrual loans	2,104	2,171
Commercial real estate [Member] | All other [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
Nonaccrual loans	2,117	2,117
Residential mortgage loans [Member] | Multi-family [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
Nonaccrual loans	453	0
Residential mortgage loans [Member] | Single family [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
Nonaccrual loans	1,187	1,472
Land development loans [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
Nonaccrual loans	$ 1,685	$ 2,111