Allowance for Loan and Lease Losses - Allowance for Credit Losses - Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 9,883		$ 9,750	$ 9,043
Charge-offs	(697)	$ (2,644)		(5,308)
Recoveries	664		2,044	1,665
Provision	1,350		2,050	4,350
Ending balance	11,200	9,750	11,200	9,750
Unallocated [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	12		30	46
Provision	(14)		(32)	(16)
Ending balance	(2)	30	(2)	30
Real Estate Sector [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5,969		5,831	4,786
Charge-offs				(2,474)
Recoveries	187		516	374
Provision	568		377	3,145
Ending balance	6,724	5,831	6,724	5,831
Agricultural Sector [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	201		256	208
Recoveries				23
Provision	(10)		(65)	25
Ending balance	191	256	191	256
Commercial and Industrial and Mortgage Warehouse Sector [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2,569		2,394	2,772
Charge-offs	(57)	(891)		(608)
Recoveries	172		646	148
Provision	177		712	82
Ending balance	2,861	2,394	2,861	2,394
Consumer Loans Sector [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,132		1,239	1,231
Charge-offs	(640)	(1,753)		(2,226)
Recoveries	305		882	1,120
Provision	629		1,058	1,114
Ending balance	$ 1,426	$ 1,239	$ 1,426	$ 1,239