Loans and Allowance for Credit Losses - Summary of Loan Classes and Aging of Past Due Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	$ 99,644	$ 79,910
Nonaccrual Loans	87,823	56,347
Current	16,004,007	13,351,812
Total Loans	16,103,651
Total Loans	16,103,651	13,431,722	$ 12,178,150
30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	9,869	21,494
Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,952	2,069
Commercial and Industrial Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	38,740
Nonaccrual Loans	33,769
Current	7,023,334
Total Loans	7,062,074
Commercial and Industrial Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,652
Commercial and Industrial Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	319
Specialty Lending Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	19,437
Nonaccrual Loans	19,437
Current	491,863
Total Loans	511,300
Specialty Lending Portfolio [Member] | Asset-based [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	355,349
Specialty Lending Portfolio [Member] | Factoring [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	155,951
Commercial Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	30,962
Nonaccrual Loans	28,386
Current	5,877,972
Total Loans	5,908,934
Commercial Real Estate Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	2,351
Commercial Real Estate Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	225
Consumer Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	5,869
Nonaccrual Loans	5,345
Current	1,939,625
Total Loans	1,945,494
Consumer Real Estate Portfolio [Member] | HELOC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	395,169
Consumer Real Estate Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	524
Consumer Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	489
Nonaccrual Loans	88
Current	117,497
Total Loans	117,986
Total Loans		360,216	375,767
Consumer Portfolio [Member] | Consumer Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		4,319
Nonaccrual Loans		803
Current		222,423
Total Loans		226,742
Consumer Portfolio [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		388
Nonaccrual Loans		257
Current		133,086
Total Loans		133,474
Consumer Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	281
Consumer Portfolio [Member] | 30-89 Days Past Due and Accruing [Member] | Consumer Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		1,835
Consumer Portfolio [Member] | 30-89 Days Past Due and Accruing [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		81
Consumer Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	120
Consumer Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member] | Consumer Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		1,681
Consumer Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		50
Credit Cards Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,147
Nonaccrual Loans	798
Current	362,821
Total Loans	366,968
Credit Cards Portfolio [Member] | Commercial Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	7,875
Current	170,412
Total Loans	178,287
Credit Cards Portfolio [Member] | Consumer Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	188,681
Credit Cards Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	2,061
Credit Cards Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,288
Leases and Other Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	190,895
Total Loans	190,895
Leases and Other Portfolio [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 188,482
Commercial Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans		6,487,031	6,037,065
Commercial Portfolio [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		36,333
Nonaccrual Loans		25,592
Current		5,805,669
Total Loans		5,842,002
Commercial Portfolio [Member] | Asset-based [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current		292,231
Total Loans		292,231
Commercial Portfolio [Member] | Factoring [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current		170,560
Total Loans		170,560
Commercial Portfolio [Member] | Commercial Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		836
Nonaccrual Loans		24
Current		181,402
Total Loans		182,238
Commercial Portfolio [Member] | 30-89 Days Past Due and Accruing [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		10,491
Commercial Portfolio [Member] | 30-89 Days Past Due and Accruing [Member] | Commercial Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		760
Commercial Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		250
Commercial Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member] | Commercial Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		52
Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans		6,582,497	5,760,070
Real Estate Portfolio [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		4,028
Nonaccrual Loans		95
Current		838,318
Total Loans		842,346
Real Estate Portfolio [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		27,431
Nonaccrual Loans		24,030
Current		4,301,293
Total Loans		4,328,724
Real Estate Portfolio [Member] | Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		3,233
Nonaccrual Loans		2,748
Current		930,043
Total Loans		933,276
Real Estate Portfolio [Member] | HELOC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		3,342
Nonaccrual Loans		2,798
Current		474,809
Total Loans		478,151
Real Estate Portfolio [Member] | 30-89 Days Past Due and Accruing [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		3,933
Real Estate Portfolio [Member] | 30-89 Days Past Due and Accruing [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		3,365
Real Estate Portfolio [Member] | 30-89 Days Past Due and Accruing [Member] | Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		485
Real Estate Portfolio [Member] | 30-89 Days Past Due and Accruing [Member] | HELOC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		544
Real Estate Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		36
Leases Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current		1,978
Total Loans		$ 1,978	$ 5,248