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	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	$ 139,160	$ 82,269
Non-accrual Loans With No Related Allowance	61,383
Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	122,964
Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	49,954
Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	3,169
Commercial Industrial And Agricultural | Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	28,349	29,995
Non-accrual Loans With No Related Allowance	6,338
Commercial Industrial And Agricultural | Commercial and industrial | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	6,870
Commercial Industrial And Agricultural | Commercial and industrial | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	45,235
Commercial Industrial And Agricultural | Commercial and industrial | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	3,169
Commercial Industrial And Agricultural | Agricultural
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	8,494	5,954
Non-accrual Loans With No Related Allowance	4,485
Commercial Industrial And Agricultural | Agricultural | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	3,417
Commercial Industrial And Agricultural | Agricultural | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	4,719
Commercial Industrial And Agricultural | Agricultural | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	0
Commercial Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	84,690	33,435
Non-accrual Loans With No Related Allowance	49,910
Commercial Real Estate | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	109,768
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	35,915	25,857
Non-accrual Loans With No Related Allowance	17,293
Commercial Real Estate | Office, retail, and industrial | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	44,538
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	3,121	2,697
Non-accrual Loans With No Related Allowance	1,785
Commercial Real Estate | Multi-family | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,606
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	27,282	152
Non-accrual Loans With No Related Allowance	19,043
Commercial Real Estate | Construction | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	28,779
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	18,372	4,729
Non-accrual Loans With No Related Allowance	11,789
Commercial Real Estate | Other commercial real estate | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	33,845
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	121,533	69,384
Non-accrual Loans With No Related Allowance	60,733
Total corporate loans | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	120,055
Total corporate loans | Blanket Lien
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	49,954
Total corporate loans | Equipment
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	3,169
Consumer loans
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	17,627	12,885
Non-accrual Loans With No Related Allowance	650
Consumer loans | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,909
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	9,129	8,443
Non-accrual Loans With No Related Allowance	123
Consumer loans | Home equity | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	244
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	8,498	4,442
Non-accrual Loans With No Related Allowance	527
Consumer loans | 1-4 family mortgages | Real Estate
Financing Receivable, Nonaccrual [Line Items]
Non-accrual	2,665
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