Loans and the Allowance for Credit Losses - Schedule of Recorded Investment in Loans by Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	$ 10,789,233	$ 10,267,985
Loans held for sale	168,378	43,013
Total loans	10,957,611	10,310,998
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	1,681,182	1,644,699
Commercial And Industrial - PPP [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	726,256
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	5,705,392	5,725,008
Commercial Real Estate [Member] | Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	668,277	777,151
Commercial Real Estate [Member] | Commercial Real Estate - Improved Property [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	5,037,115	4,947,857
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	1,720,961	1,873,647
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	309,055	374,953
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	$ 646,387	$ 649,678