Loans - Schedule of Loans Renegotiated in Troubled Debt Restructurings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) notes	Dec. 31, 2014 USD ($) notes	Dec. 31, 2013 USD ($) notes
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	3
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 244
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	0	$ 0	$ 0
Loans renegotiated in troubled debt restructurings	40,330	44,227
Loans renegotiated in troubled debt restructurings, non-accrual loans	24,911	23,275
Loans tenegotiated in troubled debt restructurings, accrual loans	$ 15,419	$ 20,952
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	15	20	43
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 13,148	$ 7,190	$ 28,403
Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	2	13	19
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 682	$ 6,556	$ 15,651
Land acquisition & development construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes			8
Financing Receivable, Modifications, Pre-Modification Recorded Investment			$ 9,788
Residential construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes			3
Financing Receivable, Modifications, Pre-Modification Recorded Investment			$ 819
Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes			11
Financing Receivable, Modifications, Pre-Modification Recorded Investment			$ 10,607
Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes		1	5
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 15	$ 787
Agricultural 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			$ 188
Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period | notes		14	36
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 6,571	$ 27,233
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		$ 113	$ 27
Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 4
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	1
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 4
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 240
Financing receivable, modifications, subsequent default, number of contracts, during period | notes	12	5	6
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 12,462	$ 506	$ 1,143
Interest Only Period Concession [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0	5,229	1,684
Interest Only Period Concession [Member] | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0	4,753	543
Interest Only Period Concession [Member] | Land acquisition & development construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			528
Interest Only Period Concession [Member] | Residential construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			0
Interest Only Period Concession [Member] | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			528
Interest Only Period Concession [Member] | Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		0	0
Interest Only Period Concession [Member] | Agricultural 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	1,071
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] | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Interest Only Period Concession [Member] | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0	476	613
Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	3,318	84	14,263
Interest rate adjustment | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0	84	11,420
Interest rate adjustment | Land acquisition & development construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			1,952
Interest rate adjustment | Residential construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			411
Interest rate adjustment | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			2,363
Interest rate adjustment | Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		0	0
Interest rate adjustment | Agricultural real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			188
Interest rate adjustment | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		84	13,971
Interest rate adjustment | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		0	27
Interest rate adjustment | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Interest rate adjustment | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	3,318	0	265
Other Concession [Member]
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	513	1,092	2,476
Other Concession [Member] | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	54	1,047	2,310
Other Concession [Member] | Land acquisition & development construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			0
Other Concession [Member] | Residential construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			0
Other Concession [Member] | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			0
Other Concession [Member] | Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		15	79
Other Concession [Member] | Agricultural real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			0
Other Concession [Member] | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		1,062	2,389
Other Concession [Member] | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		0	0
Other Concession [Member] | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	4
Other Concession [Member] | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	455	30	87
Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	9,317	785	9,980
Extension of terms or maturity | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	628	672	1,378
Extension of terms or maturity | Land acquisition & development construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			7,308
Extension of terms or maturity | Residential construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			408
Extension of terms or maturity | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment			7,716
Extension of terms or maturity | Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		0	708
Extension of terms or maturity | Agricultural 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	9,802
Extension of terms or maturity | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment		113	0
Extension of terms or maturity | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0
Extension of terms or maturity | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 8,689	$ 0	$ 178