Past Due Loans, Allowance For Credit Losses, Non-Accrual Loans, and TDRS - Collateral-dependent Loans and Non-accrual Loans With No Related Allowance by Class (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	$ 143,572	$ 82,269
Non-accrual Loans With No Related Allowance	79,375
Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	126,072
Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	42,438
Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,484
Commercial industrial and agricultural | Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	49,866	29,995
Non-accrual Loans With No Related Allowance	39,507
Commercial industrial and agricultural | Commercial and industrial | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	27,238
Commercial industrial and agricultural | Commercial and industrial | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	39,761
Commercial industrial and agricultural | Commercial and industrial | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,484
Commercial industrial and agricultural | Agricultural
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	13,293	5,954
Non-accrual Loans With No Related Allowance	2,406
Commercial industrial and agricultural | Agricultural | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	10,259
Commercial industrial and agricultural | Agricultural | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,677
Commercial industrial and agricultural | Agricultural | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	61,795	33,435
Non-accrual Loans With No Related Allowance	36,787
Commercial real estate | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	85,603
Commercial real estate | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Office, retail, and industrial
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	35,241	25,857
Non-accrual Loans With No Related Allowance	21,756
Commercial real estate | Office, retail, and industrial | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	43,834
Commercial real estate | Office, retail, and industrial | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Office, retail, and industrial | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Multi-family
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,433	2,697
Non-accrual Loans With No Related Allowance	1,280
Commercial real estate | Multi-family | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,116
Commercial real estate | Multi-family | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Multi-family | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Construction
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	6,446	152
Non-accrual Loans With No Related Allowance	3,280
Commercial real estate | Construction | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	6,848
Commercial real estate | Construction | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Construction | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Other commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	17,675	4,729
Non-accrual Loans With No Related Allowance	10,471
Commercial real estate | Other commercial real estate | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	32,805
Commercial real estate | Other commercial real estate | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial real estate | Other commercial real estate | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Total corporate loans
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	124,954	69,384
Non-accrual Loans With No Related Allowance	78,700
Total corporate loans | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	123,100
Total corporate loans | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	42,438
Total corporate loans | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,484
Consumer loans
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	18,618	12,885
Non-accrual Loans With No Related Allowance	675
Consumer loans | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,972
Consumer loans | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Consumer loans | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Consumer loans | Home equity
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	9,548	8,443
Non-accrual Loans With No Related Allowance	123
Consumer loans | Home equity | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	247
Consumer loans | Home equity | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Consumer loans | Home equity | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Consumer loans | 1-4 family mortgages
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	9,070	4,442
Non-accrual Loans With No Related Allowance	552
Consumer loans | 1-4 family mortgages | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,725
Consumer loans | 1-4 family mortgages | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Consumer loans | 1-4 family mortgages | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Consumer loans | Installment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0	$ 0
Non-accrual Loans With No Related Allowance	0
Consumer loans | Installment | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Consumer loans | Installment | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Consumer loans | Installment | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	$ 0