Loans - Amounts of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 3,867,383		$ 3,634,596
Allowance for Loan Losses	57,027	$ 22,577	17,667
Carrying Amount	3,810,356
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,192,271		2,047,646
Allowance for Loan Losses	42,210		11,996
Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,019,912		920,998
Allowance for Loan Losses	4,620		923
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	655,200		665,952
Allowance for Loan Losses	$ 8,930		3,671
Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			14,630
Allowance for Loan Losses			133
Carrying Amount			14,497
Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			10,205
Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			3,443
Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			982
Heartland | Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			296
Allowance for Loan Losses			0
Carrying Amount			296
Heartland | Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			197
Heartland | Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			99
Heartland | Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			0
Summit | Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			561
Allowance for Loan Losses			0
Carrying Amount			561
Summit | Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			88
Summit | Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			473
Summit | Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			0
Peoples | Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			264
Allowance for Loan Losses			0
Carrying Amount			264
Peoples | Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			229
Peoples | Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			35
Peoples | Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			0
Kosciusko | Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			375
Allowance for Loan Losses			0
Carrying Amount			375
Kosciusko | Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			244
Kosciusko | Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			131
Kosciusko | Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			0
LaPorte | Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			1,166
Allowance for Loan Losses			0
Carrying Amount			1,166
LaPorte | Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			353
LaPorte | Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			793
LaPorte | Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			20
Lafayette | Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			1,867
Allowance for Loan Losses			0
Carrying Amount			1,867
Lafayette | Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			1,867
Lafayette | Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			0
Lafayette | Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			0
Wolverine | Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			2,289
Allowance for Loan Losses			0
Carrying Amount			2,289
Wolverine | Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			2,289
Wolverine | Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			0
Wolverine | Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			0
Salin | Loans Purchased With Evidence of Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			7,812
Allowance for Loan Losses			133
Carrying Amount			7,679
Salin | Loans Purchased With Evidence of Credit Deterioration | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			4,938
Salin | Loans Purchased With Evidence of Credit Deterioration | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			1,912
Salin | Loans Purchased With Evidence of Credit Deterioration | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans			$ 962