Loans - Amounts of Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Balance	$ 3,978,382	$ 3,634,596
Total loans		3,636,841
Allowance for loan losses	(55,090)	(17,667)
Loans, net	3,923,292	3,619,174
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		2,046,651
Loan Balance	2,312,715	2,047,646
Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real Estate, Total		770,717
Loan Balance	1,004,796	920,998
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		669,180
Loan Balance	660,871	665,952
Working capital and equipment | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		938,317
Real estate, including agriculture | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		978,891
Tax exempt | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		63,571
Other | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		65,872
1-4 family | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real Estate, Total		762,571
Other | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real Estate, Total		8,146
Auto | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		362,729
Recreation | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		16,262
Real estate/home improvement | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		43,585
Home equity | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		237,979
Loan Balance	$ 260,715	276,215
Unsecured | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		7,286
Other | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial/Consumer, Total		1,339
Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Balance		$ 150,293