Composition of Loan Portfolio (Parenthetical) (Detail) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		$ 37,335,541	$ 35,740,489
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	[1]	1,775,295	1,450,556
Commercial and Industrial | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		1,301,814	1,085,529
Lease financing, unearned income
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned income		52,788	43,553
Non-Covered Loans		473,481	365,027
Specialty Finance Loans | Commercial and Industrial | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		1,100,000	880,700
Other Commercial and Industrial Loans | Commercial and Industrial | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		$ 630,700	$ 569,900

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