Loans and Leases Held for Investment and Credit Quality - Loans and Leases Classified as Impaired (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Impaired loans	$ 151,647	$ 102,414
Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	103,818	72,367
Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	47,829	30,047
Commercial & Industrial
Financing Receivable, Impaired [Line Items]
Impaired loans	34,434	28,659
Commercial & Industrial | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	22,153	21,675
Commercial & Industrial | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	12,281	6,984
Commercial & Industrial | Agriculture
Financing Receivable, Impaired [Line Items]
Impaired loans	455	7
Commercial & Industrial | Agriculture | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	289
Commercial & Industrial | Agriculture | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	166	7
Commercial & Industrial | Healthcare
Financing Receivable, Impaired [Line Items]
Impaired loans	8,023	9,668
Commercial & Industrial | Healthcare | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	5,516	7,229
Commercial & Industrial | Healthcare | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	2,507	2,439
Commercial & Industrial | Independent Pharmacies
Financing Receivable, Impaired [Line Items]
Impaired loans	6,148	9,356
Commercial & Industrial | Independent Pharmacies | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	5,187	7,896
Commercial & Industrial | Independent Pharmacies | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	961	1,460
Commercial & Industrial | Registered Investment Advisors
Financing Receivable, Impaired [Line Items]
Impaired loans	1,506	3,347
Commercial & Industrial | Registered Investment Advisors | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	956	2,427
Commercial & Industrial | Registered Investment Advisors | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	550	920
Commercial & Industrial | Veterinary Industry
Financing Receivable, Impaired [Line Items]
Impaired loans	2,645	2,326
Commercial & Industrial | Veterinary Industry | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	2,186	1,819
Commercial & Industrial | Veterinary Industry | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	459	507
Commercial & Industrial | Other Industries
Financing Receivable, Impaired [Line Items]
Impaired loans	15,657	3,949
Commercial & Industrial | Other Industries | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	8,019	2,304
Commercial & Industrial | Other Industries | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	7,638	1,645
Commercial & Industrial | Funeral Home & Cemetery
Financing Receivable, Impaired [Line Items]
Impaired loans		6
Commercial & Industrial | Funeral Home & Cemetery | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans		6
Construction & Development
Financing Receivable, Impaired [Line Items]
Impaired loans	719	5,027
Construction & Development | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	530	3,704
Construction & Development | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	189	1,323
Construction & Development | Agriculture
Financing Receivable, Impaired [Line Items]
Impaired loans		5,027
Construction & Development | Agriculture | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans		3,704
Construction & Development | Agriculture | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans		1,323
Construction & Development | Healthcare
Financing Receivable, Impaired [Line Items]
Impaired loans	719
Construction & Development | Healthcare | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	530
Construction & Development | Healthcare | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	189
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Impaired loans	70,873	46,731
Commercial Real Estate | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	47,014	33,811
Commercial Real Estate | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	23,859	12,920
Commercial Real Estate | Agriculture
Financing Receivable, Impaired [Line Items]
Impaired loans	2,085	1,798
Commercial Real Estate | Agriculture | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	1,564	1,299
Commercial Real Estate | Agriculture | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	521	499
Commercial Real Estate | Healthcare
Financing Receivable, Impaired [Line Items]
Impaired loans	29,676	20,442
Commercial Real Estate | Healthcare | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	17,025	14,559
Commercial Real Estate | Healthcare | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	12,651	5,883
Commercial Real Estate | Independent Pharmacies
Financing Receivable, Impaired [Line Items]
Impaired loans	7,964	5,633
Commercial Real Estate | Independent Pharmacies | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	6,662	4,079
Commercial Real Estate | Independent Pharmacies | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	1,302	1,554
Commercial Real Estate | Veterinary Industry
Financing Receivable, Impaired [Line Items]
Impaired loans	12,648	15,715
Commercial Real Estate | Veterinary Industry | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	8,850	11,613
Commercial Real Estate | Veterinary Industry | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	3,798	4,102
Commercial Real Estate | Other Industries
Financing Receivable, Impaired [Line Items]
Impaired loans	16,720
Commercial Real Estate | Other Industries | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	11,620
Commercial Real Estate | Other Industries | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	5,100
Commercial Real Estate | Funeral Home & Cemetery
Financing Receivable, Impaired [Line Items]
Impaired loans	1,780	3,143
Commercial Real Estate | Funeral Home & Cemetery | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	1,293	2,261
Commercial Real Estate | Funeral Home & Cemetery | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	487	882
Commercial Land
Financing Receivable, Impaired [Line Items]
Impaired loans	45,621	21,997
Commercial Land | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	34,121	13,177
Commercial Land | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	11,500	8,820
Commercial Land | Agriculture
Financing Receivable, Impaired [Line Items]
Impaired loans	45,621	21,997
Commercial Land | Agriculture | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Impaired [Line Items]
Impaired loans	34,121	13,177
Commercial Land | Agriculture | Unguaranteed Exposure
Financing Receivable, Impaired [Line Items]
Impaired loans	$ 11,500	$ 8,820