Loans and Allowance for Credit Losses - Summary of Loan Classes and Aging of Past Due Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	$ 108,280	$ 79,910
Non- Accrual Loans	82,245	56,347
Current	15,196,817	13,351,812
Total Loans	15,305,097
Total Loans	15,305,097	13,431,722	$ 12,900,269
30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	21,447	21,494
Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	4,588	2,069
Commercial and Industrial Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	53,167
Non- Accrual Loans	39,982
Current	6,947,002
Total Loans	7,000,169
Commercial and Industrial Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	12,505
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	680
Specialty Lending Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	538
Non- Accrual Loans	538
Current	413,168
Total Loans	413,706
Specialty Lending Portfolio [Member] | Asset-based [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	297,080
Specialty Lending Portfolio [Member] | Factoring [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	116,626
Commercial Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	43,381
Non- Accrual Loans	35,531
Current	5,525,306
Total Loans	5,568,687
Commercial Real Estate Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	5,490
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	2,360
Consumer Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	6,464
Non- Accrual Loans	5,148
Current	1,624,096
Total Loans	1,630,560
Consumer Real Estate Portfolio [Member] | HELOC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	430,108
Consumer Real Estate Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,316
Consumer Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,156
Non- Accrual Loans	208
Current	154,625
Total Loans	155,781
Total Loans			355,736
Consumer Portfolio [Member] | Consumer Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		4,319
Non- Accrual 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
Non- Accrual 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	870
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	78
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	3,551
Non- Accrual Loans	815
Current	336,936
Total Loans	340,487
Credit Cards Portfolio [Member] | Commercial Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	5,945
Current	140,108
Total Loans	146,053
Credit Cards Portfolio [Member] | Consumer Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	194,434
Credit Cards Portfolio [Member] | 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,266
Credit Cards Portfolio [Member] | Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,470
Leases and Other Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	23
Non- Accrual Loans	23
Current	195,684
Total Loans	195,707
Leases and Other Portfolio [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 193,565
Commercial Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans			6,356,633
Commercial Portfolio [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		36,333
Non- Accrual 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
Non- Accrual 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
Leases Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current		1,978
Total Loans		1,978	4,733
Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans			$ 6,183,167
Real Estate Portfolio [Member] | Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		4,028
Non- Accrual 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
Non- Accrual 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
Non- Accrual 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
Non- Accrual 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