Loans and Allowance for Credit Losses - Summary of Amortized Cost Balance of Each of Loan Classes Disaggregated by Collateral Type and Origination Year (Detail) $ in Thousands	Jun. 30, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	$ 4,227,558
Amortized Cost Basis by Origination Year 2019	2,358,208
Amortized Cost Basis by Origination Year 2018	1,380,748
Amortized Cost Basis by Origination Year 2017	908,841
Amortized Cost Basis by Origination Year 2016	903,614
Amortized Cost Basis by Origination Year Prior to 2016	762,301
Amortized Cost - Revolving Loans	4,523,939
Amortized Cost - Revolving Loans Converted to Term Loans	239,888
Total Loans	15,305,097
Commercial and Industrial Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	2,751,530
Amortized Cost Basis by Origination Year 2019	898,634
Amortized Cost Basis by Origination Year 2018	607,147
Amortized Cost Basis by Origination Year 2017	245,316
Amortized Cost Basis by Origination Year 2016	212,795
Amortized Cost Basis by Origination Year Prior to 2016	134,650
Amortized Cost - Revolving Loans	2,144,429
Amortized Cost - Revolving Loans Converted to Term Loans	5,668
Total Loans	7,000,169
Commercial and Industrial Portfolio [Member] | Equipment/Accounts Receivable/Inventory [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	2,747,391
Amortized Cost Basis by Origination Year 2019	888,198
Amortized Cost Basis by Origination Year 2018	604,472
Amortized Cost Basis by Origination Year 2017	239,238
Amortized Cost Basis by Origination Year 2016	209,719
Amortized Cost Basis by Origination Year Prior to 2016	133,629
Amortized Cost - Revolving Loans	1,958,136
Amortized Cost - Revolving Loans Converted to Term Loans	5,668
Total Loans	6,786,451
Commercial and Industrial Portfolio [Member] | Agriculture [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	4,139
Amortized Cost Basis by Origination Year 2019	10,436
Amortized Cost Basis by Origination Year 2018	2,675
Amortized Cost Basis by Origination Year 2017	6,078
Amortized Cost Basis by Origination Year 2016	3,076
Amortized Cost Basis by Origination Year Prior to 2016	1,021
Amortized Cost - Revolving Loans	141,231
Total Loans	168,656
Commercial and Industrial Portfolio [Member] | Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost - Revolving Loans	45,062
Total Loans	45,062
Specialty Lending Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	10,549
Amortized Cost Basis by Origination Year 2019	58,741
Amortized Cost - Revolving Loans	344,416
Total Loans	413,706
Specialty Lending Portfolio [Member] | Asset-based Lending [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	10,549
Amortized Cost Basis by Origination Year 2019	58,741
Amortized Cost - Revolving Loans	227,790
Total Loans	297,080
Specialty Lending Portfolio [Member] | Factoring [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost - Revolving Loans	116,626
Total Loans	116,626
Commercial Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	983,639
Amortized Cost Basis by Origination Year 2019	1,004,346
Amortized Cost Basis by Origination Year 2018	644,149
Amortized Cost Basis by Origination Year 2017	538,551
Amortized Cost Basis by Origination Year 2016	588,876
Amortized Cost Basis by Origination Year Prior to 2016	513,088
Amortized Cost - Revolving Loans	1,062,855
Amortized Cost - Revolving Loans Converted to Term Loans	233,183
Total Loans	5,568,687
Commercial Real Estate Portfolio [Member] | Owner-occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	316,187
Amortized Cost Basis by Origination Year 2019	371,127
Amortized Cost Basis by Origination Year 2018	272,386
Amortized Cost Basis by Origination Year 2017	209,485
Amortized Cost Basis by Origination Year 2016	147,403
Amortized Cost Basis by Origination Year Prior to 2016	244,285
Amortized Cost - Revolving Loans	21,619
Amortized Cost - Revolving Loans Converted to Term Loans	26,545
Total Loans	1,609,037
Commercial Real Estate Portfolio [Member] | Non-owner-occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	348,982
Amortized Cost Basis by Origination Year 2019	509,523
Amortized Cost Basis by Origination Year 2018	274,344
Amortized Cost Basis by Origination Year 2017	239,342
Amortized Cost Basis by Origination Year 2016	271,723
Amortized Cost Basis by Origination Year Prior to 2016	198,205
Amortized Cost - Revolving Loans	37,887
Amortized Cost - Revolving Loans Converted to Term Loans	204,242
Total Loans	2,084,248
Commercial Real Estate Portfolio [Member] | Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	197,996
Amortized Cost Basis by Origination Year 2019	58,802
Amortized Cost Basis by Origination Year 2018	44,180
Amortized Cost Basis by Origination Year 2017	46,725
Amortized Cost Basis by Origination Year 2016	58,669
Amortized Cost Basis by Origination Year Prior to 2016	56,551
Amortized Cost - Revolving Loans	44,248
Total Loans	507,171
Commercial Real Estate Portfolio [Member] | 5+ Multi-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	108,935
Amortized Cost Basis by Origination Year 2019	61,089
Amortized Cost Basis by Origination Year 2018	47,415
Amortized Cost Basis by Origination Year 2017	42,479
Amortized Cost Basis by Origination Year 2016	110,554
Amortized Cost Basis by Origination Year Prior to 2016	11,162
Amortized Cost - Revolving Loans	1,582
Total Loans	383,216
Commercial Real Estate Portfolio [Member] | 1-4 Family Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost - Revolving Loans	39,126
Total Loans	39,126
Commercial Real Estate Portfolio [Member] | General Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	11,539
Amortized Cost Basis by Origination Year 2019	3,805
Amortized Cost Basis by Origination Year 2018	5,824
Amortized Cost Basis by Origination Year 2017	520
Amortized Cost Basis by Origination Year 2016	527
Amortized Cost Basis by Origination Year Prior to 2016	2,885
Amortized Cost - Revolving Loans	918,393
Amortized Cost - Revolving Loans Converted to Term Loans	2,396
Total Loans	945,889
Consumer Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	462,053
Amortized Cost Basis by Origination Year 2019	367,329
Amortized Cost Basis by Origination Year 2018	113,712
Amortized Cost Basis by Origination Year 2017	118,044
Amortized Cost Basis by Origination Year 2016	98,028
Amortized Cost Basis by Origination Year Prior to 2016	106,985
Amortized Cost - Revolving Loans	363,372
Amortized Cost - Revolving Loans Converted to Term Loans	1,037
Total Loans	1,630,560
Consumer Real Estate Portfolio [Member] | HELOC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	38,600
Amortized Cost Basis by Origination Year 2019	16,301
Amortized Cost Basis by Origination Year 2018	9,158
Amortized Cost Basis by Origination Year 2017	446
Amortized Cost Basis by Origination Year 2016	84
Amortized Cost Basis by Origination Year Prior to 2016	2,791
Amortized Cost - Revolving Loans	362,728
Total Loans	430,108
Consumer Real Estate Portfolio [Member] | First Lien: 1-4 Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	418,194
Amortized Cost Basis by Origination Year 2019	342,737
Amortized Cost Basis by Origination Year 2018	101,371
Amortized Cost Basis by Origination Year 2017	115,564
Amortized Cost Basis by Origination Year 2016	96,794
Amortized Cost Basis by Origination Year Prior to 2016	102,244
Amortized Cost - Revolving Loans	353
Amortized Cost - Revolving Loans Converted to Term Loans	1,037
Total Loans	1,178,294
Consumer Real Estate Portfolio [Member] | Junior Lien: 1-4 Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	5,259
Amortized Cost Basis by Origination Year 2019	8,291
Amortized Cost Basis by Origination Year 2018	3,183
Amortized Cost Basis by Origination Year 2017	2,034
Amortized Cost Basis by Origination Year 2016	1,150
Amortized Cost Basis by Origination Year Prior to 2016	1,950
Amortized Cost - Revolving Loans	291
Total Loans	22,158
Consumer Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	9,933
Amortized Cost Basis by Origination Year 2019	16,637
Amortized Cost Basis by Origination Year 2018	7,168
Amortized Cost Basis by Origination Year 2017	3,005
Amortized Cost Basis by Origination Year 2016	2,385
Amortized Cost Basis by Origination Year Prior to 2016	1,035
Amortized Cost - Revolving Loans	115,618
Total Loans	155,781
Consumer Portfolio [Member] | Revolving Line [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost - Revolving Loans	94,333
Total Loans	94,333
Consumer Portfolio [Member] | Auto [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	7,377
Amortized Cost Basis by Origination Year 2019	12,530
Amortized Cost Basis by Origination Year 2018	4,308
Amortized Cost Basis by Origination Year 2017	2,456
Amortized Cost Basis by Origination Year 2016	1,212
Amortized Cost Basis by Origination Year Prior to 2016	729
Total Loans	28,612
Consumer Portfolio [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	2,556
Amortized Cost Basis by Origination Year 2019	4,107
Amortized Cost Basis by Origination Year 2018	2,860
Amortized Cost Basis by Origination Year 2017	549
Amortized Cost Basis by Origination Year 2016	1,173
Amortized Cost Basis by Origination Year Prior to 2016	306
Amortized Cost - Revolving Loans	21,285
Total Loans	32,836
Credit Cards Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost - Revolving Loans	340,487
Total Loans	340,487
Credit Cards Portfolio [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost - Revolving Loans	194,434
Total Loans	194,434
Credit Cards Portfolio [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost - Revolving Loans	146,053
Total Loans	146,053
Leases and Other Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	9,854
Amortized Cost Basis by Origination Year 2019	12,521
Amortized Cost Basis by Origination Year 2018	8,572
Amortized Cost Basis by Origination Year 2017	3,925
Amortized Cost Basis by Origination Year 2016	1,530
Amortized Cost Basis by Origination Year Prior to 2016	6,543
Amortized Cost - Revolving Loans	152,762
Total Loans	195,707
Leases and Other Portfolio [Member] | Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2019	557
Amortized Cost Basis by Origination Year 2017	833
Amortized Cost Basis by Origination Year Prior to 2016	752
Total Loans	2,142
Leases and Other Portfolio [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost Basis by Origination Year 2020	9,854
Amortized Cost Basis by Origination Year 2019	11,964
Amortized Cost Basis by Origination Year 2018	8,572
Amortized Cost Basis by Origination Year 2017	3,092
Amortized Cost Basis by Origination Year 2016	1,530
Amortized Cost Basis by Origination Year Prior to 2016	5,791
Amortized Cost - Revolving Loans	152,762
Total Loans	$ 193,565