Loans and Allowance for Credit Losses - Credit Risk Profile by Risk Rating (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	$ 15,305,097	$ 13,431,722	$ 12,900,269
Commercial [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		5,842,002
Commercial [Member] | Originated and Non-PCI Loans [Member] | Non-watch List-Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		5,380,205
Commercial [Member] | Originated and Non-PCI Loans [Member] | Watch-Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		257,040
Commercial [Member] | Originated and Non-PCI Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		91,020
Commercial [Member] | Originated and Non-PCI Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		113,737
Asset-based [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		292,231
Asset-based [Member] | Originated and Non-PCI Loans [Member] | Non-watch List-Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		230,526
Asset-based [Member] | Originated and Non-PCI Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		34,640
Asset-based [Member] | Originated and Non-PCI Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		27,065
Factoring [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		170,560
Factoring [Member] | Originated and Non-PCI Loans [Member] | Non-watch List-Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		127,310
Factoring [Member] | Originated and Non-PCI Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		1,376
Factoring [Member] | Originated and Non-PCI Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		41,874
Real estate - construction [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		842,346
Real estate - construction [Member] | Originated and Non-PCI Loans [Member] | Non-watch List-Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		837,836
Real estate - construction [Member] | Originated and Non-PCI Loans [Member] | Watch-Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		175
Real estate - construction [Member] | Originated and Non-PCI Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		307
Real estate - construction [Member] | Originated and Non-PCI Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		4,028
Real estate - commercial [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		4,328,724
Real estate - commercial [Member] | Originated and Non-PCI Loans [Member] | Non-watch List-Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		4,078,673
Real estate - commercial [Member] | Originated and Non-PCI Loans [Member] | Watch-Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		110,530
Real estate - commercial [Member] | Originated and Non-PCI Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		28,020
Real estate - commercial [Member] | Originated and Non-PCI Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		$ 111,501