Loans Receivable, Net - Recorded Investment in Non-Accrual Loans by Loan Portfolio Segment Excluding PCI Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment in Non-accrual Loans	$ 19,239	$ 20,865
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment in Non-accrual Loans	1,727	503
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment in Non-accrual Loans	511	5,962
Commercial Real Estate - Investor
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment in Non-accrual Loans	8,082	8,281
Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment in Non-accrual Loans	6,390	4,190
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment in Non-accrual Loans	$ 2,529	$ 1,929