Loans - Schedule of Loans Renegotiated in Troubled Debt Restructurings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) notes	Dec. 31, 2015 USD ($) notes	Dec. 31, 2014 USD ($) notes
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | notes	3
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 575
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	0	$ 0	$ 0
Loans renegotiated in troubled debt restructurings	49,652	40,330
Loans renegotiated in troubled debt restructurings, non-accrual loans	27,309	24,911
Loans tenegotiated in troubled debt restructurings, accrual loans	$ 22,343	$ 15,419
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	35	15	20
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 20,066	$ 13,148	$ 7,190
Commercial Real Estate [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | notes	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 194
Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	18	2	13
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 7,837	$ 682	$ 6,556
Commercial Construction [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	1
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 3,749
Residential Portfolio Segment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	1
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 64
Real Estate Loan [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	20
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 11,650
Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes			1
Financing Receivable, Modifications, Pre-Modification Recorded Investment			$ 15
Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes			14
Financing Receivable, Modifications, Pre-Modification Recorded Investment			$ 6,571
Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes		1	1
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 4	$ 113
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 381
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	13	12	5
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 8,076	$ 12,462	$ 506
Agriculture
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	2
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 340
Interest Only Period Concession [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	4,863	0	5,229
Interest Only Period Concession [Member] | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	437	0	4,753
Interest Only Period Concession [Member] | Commercial Construction [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Interest Only Period Concession [Member] | Residential Portfolio Segment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Interest Only Period Concession [Member] | Real Estate Loan [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	437
Interest Only Period Concession [Member] | Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			0
Interest Only Period Concession [Member] | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			4,753
Interest Only Period Concession [Member] | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		0	0
Interest Only Period Concession [Member] | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	4,426	0	476
Interest Only Period Concession [Member] | Agriculture
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	171	3,318	84
Interest rate adjustment | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	171	0	84
Interest rate adjustment | Commercial Construction [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Interest rate adjustment | Residential Portfolio Segment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Interest rate adjustment | Real Estate Loan [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	171
Interest rate adjustment | Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			0
Interest rate adjustment | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			84
Interest rate adjustment | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		0	0
Interest rate adjustment | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0	3,318	0
Interest rate adjustment | Agriculture
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Other Concession [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	5,046	513	1,092
Other Concession [Member] | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	1,777	54	1,047
Other Concession [Member] | Commercial Construction [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Other Concession [Member] | Residential Portfolio Segment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Other Concession [Member] | Real Estate Loan [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	1,777
Other Concession [Member] | Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			15
Other Concession [Member] | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			1,062
Other Concession [Member] | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		4	0
Other Concession [Member] | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	3,269	455	30
Other Concession [Member] | Agriculture
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	9,986	9,317	785
Extension of terms or maturity | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	5,452	628	672
Extension of terms or maturity | Commercial Construction [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	3,749
Extension of terms or maturity | Residential Portfolio Segment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	64
Extension of terms or maturity | Real Estate Loan [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	9,265
Extension of terms or maturity | Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			0
Extension of terms or maturity | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			672
Extension of terms or maturity | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		0	113
Extension of terms or maturity | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 381	$ 8,689	$ 0