Loans and Leases - Composition of Loan and Lease Portfolio (Parenthetical) (Detail) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable		$ 119,600	$ 116,900
Non-Covered Loans		42,235,977	41,844,019
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	[1],[2]	3,437,694	3,014,378
Commercial and Industrial | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		1,953,431	1,742,380
Lease financing, unearned income
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned income		106,450	104,826
Non-Covered Loans		1,484,263	1,271,998
Specialty Finance Loans | Commercial and Industrial | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		3,000,000	2,600,000
Other Commercial and Industrial Loans | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		$ 432,800	$ 420,100

[1] Includes lease financing receivables, all of which were classified as Pass.

[2] Includes specialty finance loans and leases of $3.0 billion and $2.6 billion, respectively, at March 31, 2020 and December 31, 2019, and other C&I loans of $432.8 million and $420.1 million, respectively, at March 31, 2020 and December 31, 2019.