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, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	$ 88,083	$ 142,525
Non-accrual Loans With No Related Allowance	35,119	89,352
Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	68,377	129,295
Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	11,572	37,369
Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	923	2,555
Commercial, industrial, agricultural | Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	14,616	42,965
Non-accrual Loans With No Related Allowance	10,619	36,686
Commercial, industrial, agricultural | Commercial and industrial | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	4,296	27,007
Commercial, industrial, agricultural | Commercial and industrial | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	11,572	35,632
Commercial, industrial, agricultural | Commercial and industrial | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	923	2,555
Commercial, industrial, agricultural | Agricultural
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	6,682	10,719
Non-accrual Loans With No Related Allowance	2,784	5,213
Commercial, industrial, agricultural | Agricultural | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	6,445	8,583
Commercial, industrial, agricultural | Agricultural | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	1,737
Commercial, industrial, agricultural | Agricultural | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	43,993	67,516
Non-accrual Loans With No Related Allowance	21,620	46,776
Commercial real estate | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	56,410	90,687
Commercial real estate | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Office, retail, and industrial
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	20,632	34,224
Non-accrual Loans With No Related Allowance	11,868	23,508
Commercial real estate | Office, retail, and industrial | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	20,285	42,790
Commercial real estate | Office, retail, and industrial | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Office, retail, and industrial | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Multi- family
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	3,450	2,488
Non-accrual Loans With No Related Allowance	2,950	1,279
Commercial real estate | Multi- family | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	2,950	2,097
Commercial real estate | Multi- family | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Multi- family | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Construction
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	1,851	4,980
Non-accrual Loans With No Related Allowance	327	1,831
Commercial real estate | Construction | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	2,223	5,370
Commercial real estate | Construction | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Construction | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Other commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	18,060	25,824
Non-accrual Loans With No Related Allowance	6,475	20,158
Commercial real estate | Other commercial real estate | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	30,952	40,430
Commercial real estate | Other commercial real estate | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Commercial real estate | Other commercial real estate | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Total corporate loans
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	65,291	121,200
Non-accrual Loans With No Related Allowance	35,023	88,675
Total corporate loans | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	67,151	126,277
Total corporate loans | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	11,572	37,369
Total corporate loans | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	923	2,555
Consumer
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	22,792	21,325
Non-accrual Loans With No Related Allowance	96	677
Consumer | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	1,226	3,018
Consumer | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Consumer | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Consumer | Home equity
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	10,006	10,795
Non-accrual Loans With No Related Allowance	96	99
Consumer | Home equity | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	96	211
Consumer | Home equity | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Consumer | Home equity | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Consumer | 1-4 family mortgages
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	12,786	10,530
Non-accrual Loans With No Related Allowance	0	578
Consumer | 1-4 family mortgages | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	1,130	2,807
Consumer | 1-4 family mortgages | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Consumer | 1-4 family mortgages | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Consumer | Installment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Non-accrual Loans With No Related Allowance	0	0
Consumer | Installment | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Consumer | Installment | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	0	0
Consumer | Installment | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non- accrual	$ 0	$ 0