Loans and Leases - Schedule of Non-Covered Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	$ 24,541,632	$ 24,021,499
Commercial Loans
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	17,140,864	16,611,633
Commercial Loans | Real estate - construction
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	1,322,627	1,321,663
Commercial Loans | Real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	2,424,139	2,475,326
Commercial Loans | Real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	6,484,257	6,267,106
Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	6,909,841	6,547,538
Residential mortgage
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	4,849,119	4,739,075
Consumer and other loans
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	7,400,768	7,409,866
Consumer and other loans | Home equity
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	1,926,753	1,987,336
Consumer and other loans | Other
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	$ 624,896	$ 683,455