Loans and Leases - Schedule of Non-Covered Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	$ 22,968,295	$ 22,519,815
Commercial Loans
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	15,628,158	15,125,322
Commercial Loans | Commercial real estate - Construction
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	1,219,647	1,196,366
Commercial Loans | Commercial real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	2,408,079	2,395,822
Commercial Loans | Commercial real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	6,147,864	5,796,117
Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	5,852,568	5,737,017
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	4,415,267	4,359,156
Consumer and Other Loans
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	2,924,870	3,035,337
Consumer and Other Loans | Home Equity
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	2,220,648	2,304,694
Consumer and Other Loans | Other
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	$ 704,222	$ 730,643