Loans, Leases and Other Real Estate - Composition of Company`s Loan and Lease Portfolio (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 4,092,893	$ 3,873,895
Less: deferred fees	(3,720)	(3,297)
Loans and leases, net of deferred fees	4,089,173	3,870,598
Commercial, Secured by Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	2,776,899	2,556,601
Commercial, Industrial and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	342,775	350,228
Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	71,698	67,016
Real Estate - Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	329,625	349,581
Real Estate-Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	241,207	211,109
Home Equity and Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 330,689	$ 339,360