Loans - Major Classifications of Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 5,634,957	$ 5,632,716
Total commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,218,177	1,237,137
Total commercial real estate | Non-owner occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	850,766	866,392
Total commercial real estate | Other commercial construction and land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	194,971	196,795
Total commercial real estate | Multifamily commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	75,737	80,708
Total commercial real estate | 1-4 family residential construction and land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	96,703	93,242
Total commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,471,781	2,415,932
Total commercial | Owner occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,095,460	1,104,972
Total commercial | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,375,233	1,309,704
Total commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,088	1,256
Total consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,785,552	1,829,545
Total consumer | 1-4 family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,015,071	1,017,791
Total consumer | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	368,510	375,276
Total consumer | Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	401,971	436,478
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 159,447	$ 150,102