Credit Risk Profile by Risk Rating - Originated and Non-PCI Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	$ 9,046,126	$ 7,465,794	$ 7,103,163
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	4,087,413	3,814,009
Commercial [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	4,084,916	3,814,009
Commercial [Member] | Non-watch list [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	3,798,138	3,532,611
Commercial [Member] | Watch [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	75,905	72,283
Commercial [Member] | Special Mention [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	46,802	98,750
Commercial [Member] | Substandard [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	164,071	110,365
Asset-based [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	218,666
Asset-based [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	218,666
Asset-based [Member] | Non-watch list [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	194,028
Asset-based [Member] | Special Mention [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	23,808
Asset-based [Member] | Substandard [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	830
Factoring [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	105,978
Factoring [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	105,978
Factoring [Member] | Non-watch list [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	105,978
Real estate - construction [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	366,592	256,006
Real estate - construction [Member] | Non-watch list [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	364,464	253,895
Real estate - construction [Member] | Watch [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	170	181
Real estate - construction [Member] | Special Mention [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating		756
Real estate - construction [Member] | Substandard [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	1,958	1,174
Real estate - commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	2,491,879	1,866,301
Real estate - commercial [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	2,490,135	1,866,301
Real estate - commercial [Member] | Non-watch list [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	2,411,729	1,780,323
Real estate - commercial [Member] | Watch [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	33,341	31,984
Real estate - commercial [Member] | Special Mention [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	16,273	8,691
Real estate - commercial [Member] | Substandard [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile by Risk Rating	$ 28,792	$ 45,303