Loans and Allowance for Credit Losses - Summary of Amortized Cost Balance of Financial Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	$ 16,497,385	$ 16,103,651
Related Allowance for Credit Losses	205,773	218,583	$ 191,146	$ 101,788
Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	76,286	87,731
Related Allowance for Credit Losses	10,130	10,127
Amortized Cost of Collateral Dependent Assets with no related Allowance	33,680	41,609
Commercial and Industrial Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	7,169,405	7,062,074
Related Allowance for Credit Losses	119,568	122,700	122,532	63,313
Commercial and Industrial Portfolio [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	30,181	33,770
Related Allowance for Credit Losses	4,974	4,828
Amortized Cost of Collateral Dependent Assets with no related Allowance	11,060	9,916
Commercial and Industrial Portfolio [Member] | Equipment/Accounts Receivable/Inventory [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	7,013,292	6,884,168
Commercial and Industrial Portfolio [Member] | Equipment/Accounts Receivable/Inventory [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	27,993	29,684
Related Allowance for Credit Losses	4,974	4,828
Amortized Cost of Collateral Dependent Assets with no related Allowance	8,872	5,830
Commercial and Industrial Portfolio [Member] | Agriculture [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	144,515	161,581
Commercial and Industrial Portfolio [Member] | Agriculture [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	2,188	4,086
Amortized Cost of Collateral Dependent Assets with no related Allowance	2,188	4,086
Specialty Lending Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	520,776	511,300
Related Allowance for Credit Losses	4,673	5,219	3,549	2,545
Specialty Lending Portfolio [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	19,083	19,436
Related Allowance for Credit Losses	4,184	4,663
Amortized Cost of Collateral Dependent Assets with no related Allowance	1,674	242
Specialty Lending Portfolio [Member] | Asset-based Lending [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	368,331	355,349
Specialty Lending Portfolio [Member] | Asset-based Lending [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	17,643	17,875
Related Allowance for Credit Losses	4,184	4,490
Amortized Cost of Collateral Dependent Assets with no related Allowance	234	242
Specialty Lending Portfolio [Member] | Factoring [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	152,445	155,951
Specialty Lending Portfolio [Member] | Factoring [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	1,440	1,561
Related Allowance for Credit Losses		173
Amortized Cost of Collateral Dependent Assets with no related Allowance	1,440
Commercial Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	6,150,354	5,908,934
Related Allowance for Credit Losses	60,043	61,931	35,395	15,951
Commercial Real Estate Portfolio [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	21,493	28,587
Related Allowance for Credit Losses	972	582
Amortized Cost of Collateral Dependent Assets with no related Allowance	15,417	25,934
Commercial Real Estate Portfolio [Member] | Owner-occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	1,712,934	1,685,185
Commercial Real Estate Portfolio [Member] | Owner-occupied [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	16,261	16,539
Related Allowance for Credit Losses	255
Amortized Cost of Collateral Dependent Assets with no related Allowance	10,869	16,539
Commercial Real Estate Portfolio [Member] | Non-owner-occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	2,691,313	2,472,535
Commercial Real Estate Portfolio [Member] | Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	494,182	502,463
Commercial Real Estate Portfolio [Member] | Farmland [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	1,829	8,625
Amortized Cost of Collateral Dependent Assets with no related Allowance	1,829	8,625
Commercial Real Estate Portfolio [Member] | 5+ Multi-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	387,748	449,855
Commercial Real Estate Portfolio [Member] | 1-4 Family Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	39,046	30,275
Commercial Real Estate Portfolio [Member] | General Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	825,131	768,621
Commercial Real Estate Portfolio [Member] | General Construction [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	3,403	3,423
Related Allowance for Credit Losses	717	582
Amortized Cost of Collateral Dependent Assets with no related Allowance	2,719	770
Consumer Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	1,999,740	1,945,494
Related Allowance for Credit Losses	4,183	6,586	4,177	2,623
Consumer Real Estate Portfolio [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	5,456	5,850
Related Allowance for Credit Losses		54
Amortized Cost of Collateral Dependent Assets with no related Allowance	5,456	5,429
Consumer Real Estate Portfolio [Member] | HELOC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	362,459	395,169
Consumer Real Estate Portfolio [Member] | HELOC [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	3,301	3,170
Amortized Cost of Collateral Dependent Assets with no related Allowance	3,301	3,170
Consumer Real Estate Portfolio [Member] | First Lien: 1-4 Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	1,616,801	1,528,494
Consumer Real Estate Portfolio [Member] | First Lien: 1-4 Family [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	1,974	2,468
Related Allowance for Credit Losses		54
Amortized Cost of Collateral Dependent Assets with no related Allowance	1,974	2,047
Consumer Real Estate Portfolio [Member] | Junior Lien: 1-4 Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	20,480	21,831
Consumer Real Estate Portfolio [Member] | Junior Lien: 1-4 Family [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	181	212
Amortized Cost of Collateral Dependent Assets with no related Allowance	181	212
Consumer Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	120,497	117,986
Related Allowance for Credit Losses	603	1,480	1,127	543
Consumer Portfolio [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	73	88
Amortized Cost of Collateral Dependent Assets with no related Allowance	73	88
Consumer Portfolio [Member] | Revolving Line [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	66,690	65,215
Consumer Portfolio [Member] | Auto [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	27,783	27,949
Consumer Portfolio [Member] | Auto [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	55	69
Amortized Cost of Collateral Dependent Assets with no related Allowance	55	69
Consumer Portfolio [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	26,024	24,822
Consumer Portfolio [Member] | Other [Member] | Collateral Dependent Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	18	19
Amortized Cost of Collateral Dependent Assets with no related Allowance	18	19
Leases and Other Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	180,107	190,895
Related Allowance for Credit Losses	1,600	2,271	$ 2,308	$ 1,074
Leases and Other Portfolio [Member] | Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	2,381	2,413
Leases and Other Portfolio [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost of Collateral Dependent Assets	$ 177,726	$ 188,482