Composition of Loan and Lease Portfolio (Parenthetical) (Detail) - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		$ 40,833,446	$ 40,133,861
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	[1]	2,776,819	2,388,420	[2]
Commercial and Industrial | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		1,767,472	1,705,308
Lease financing, unearned income
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned income		81,559	53,891
Non-Covered Loans		1,009,347	683,112
Specialty Finance Loans | Commercial and Industrial | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		2,300,000	1,900
Other Commercial and Industrial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans			$ 469,900
Other Commercial and Industrial Loans | Commercial and Industrial | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans		$ 456,100

[1] Includes specialty finance loans and leases of $2.3 billion and $1.9 billion, respectively, at June 30, 2019 and December 31, 2018. Other C&I loans of $456.1 million and $469.9 million, respectively, at June 30, 2019 and December 31, 2018.

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