Summary of Loan Classes and Aging of Past Due Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	$ 71,781	$ 86,369
Non- Accrual Loans	56,030	59,142
Current	11,559,847	11,194,144
Total Loans	11,631,628	11,280,513	$ 10,848,578
30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	12,868	24,136
Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	2,883	3,091
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	365,599		368,029
Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	19,998	23,967
Total Loans	19,998	23,967	$ 27,804
Prime [Member] | Real estate - residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,014	1,720
Non- Accrual Loans	683	929
Current	686,250	636,871
Total Loans	687,264	638,591
Prime [Member] | Real estate - residential [Member] | 30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	331	791
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	44,096	50,532
Non- Accrual Loans	37,568	38,644
Current	4,592,913	4,502,508
Total Loans	4,637,009	4,553,040
Commercial [Member] | 30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	5,709	11,216
Commercial [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	819	672
Asset-based [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	368,328	336,614
Total Loans	368,328	336,614
Factoring [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	249,351	221,672
Total Loans	249,351	221,672
Commercial - credit card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	712	466
Current	186,379	171,825
Total Loans	187,091	172,291
Commercial - credit card [Member] | 30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	676	387
Commercial - credit card [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	36	79
Construction [Member] | Real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		7,002
Non- Accrual Loans		93
Current	789,458	710,847
Total Loans	789,458	717,849
Construction [Member] | Real estate [Member] | 30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		6,666
Construction [Member] | Real estate [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		243
Real estate - commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	17,580	16,947
Non- Accrual Loans	14,245	16,115
Current	3,731,046	3,546,683
Total Loans	3,748,626	3,563,630
Real estate - commercial [Member] | 30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	3,335	832
Real estate - HELOC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	3,880	4,267
Non- Accrual Loans	3,089	3,013
Current	575,024	644,112
Total Loans	578,904	648,379
Real estate - HELOC [Member] | 30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	791	1,254
Credit card [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,138	4,524
Non- Accrual Loans	407	312
Current	223,187	248,173
Total Loans	227,325	252,697
Credit card [Member] | Consumer [Member] | 30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,875	2,155
Credit card [Member] | Consumer [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,856	2,057
Other [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	361	911
Non- Accrual Loans	38	36
Current	137,913	150,872
Total Loans	138,274	151,783
Other [Member] | Consumer [Member] | 30-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	151	835
Other [Member] | Consumer [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	$ 172	$ 40