Loans and Other Real Estate - Composition of Loan and Lease Portfolio (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 5,855,024	$ 5,140,940
Less: deferred fees	(11,433)	(3,117)
Loans, net of deferred fees	5,843,591	5,137,823
Commercial, secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,049,331	3,589,593
Commercial, industrial and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	426,821	431,934
Paycheck Protection Program ("PPP")
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	325,115	0
Equipment finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	116,410	111,076
Real estate - residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	342,583	335,191
Real estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	276,743	335,169
Home equity and consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 318,021	$ 337,977