Loans and Allowance for Loan Losses Loans and Allowance for Loan Losses - Allowance (Details)	12 Months Ended
Dec. 31, 2016 USD ($) alternative	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 08, 2016 USD ($)
Financing Receivable, Impaired [Line Items]
Minimum balance of adversely classified loan in which a detailed analysis is performed	$ 250,000
Number of alternatives for measuring impaired loans receivable \| alternative	3
Balance, beginning of year	$ 14,576,000	$ 13,682,000	$ 13,249,000
Provision for loan losses	2,826,000	1,318,000	629,000
Losses charged off	(1,675,000)	(906,000)	(537,000)
Recoveries	1,026,000	482,000	341,000
Balance, end of period	16,753,000	14,576,000	13,682,000
Individually evaluated for impairment	858,000	134,000	263,000
Collectively evaluated for impairment	15,881,000	14,442,000	13,419,000
Ending balance	1,825,992,000	1,281,889,000	1,062,406,000
Individually evaluated for impairment	5,266,000	1,174,000	3,301,000
Collectively evaluated for impairment	$ 1,812,640,000	1,280,715,000	1,059,105,000
Financing Receivable, Net				$ 8,688,000
Unsecured Open-end Loans [Member]
Financing Receivable, Impaired [Line Items]
Period When Loans Are Charged Down	180 days
Other Secured Loans [Member]
Financing Receivable, Impaired [Line Items]
Period When Loans Are Charged Down	120 days
Commercial/Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	$ 11,379,000	10,914,000	10,646,000
Provision for loan losses	1,467,000	451,000	192,000
Losses charged off	(747,000)	(289,000)	(86,000)
Recoveries	802,000	303,000	162,000
Balance, end of period	12,901,000	11,379,000	10,914,000
Individually evaluated for impairment	192,000	134,000	263,000
Collectively evaluated for impairment	12,695,000	11,245,000	10,651,000
Ending balance	1,204,799,000	807,736,000	684,552,000
Individually evaluated for impairment	1,956,000	744,000	3,301,000
Collectively evaluated for impairment	1,199,003,000	806,992,000	681,251,000
Agriculture/Agricultural Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	1,337,000	1,360,000	533,000
Provision for loan losses	933,000	(25,000)	825,000
Losses charged off	(30,000)	0	0
Recoveries	9,000	2,000	2,000
Balance, end of period	2,249,000	1,337,000	1,360,000
Individually evaluated for impairment	660,000	0	0
Collectively evaluated for impairment	1,589,000	1,337,000	1,360,000
Ending balance	212,513,000	198,066,000	178,091,000
Individually evaluated for impairment	1,345,000	430,000	0
Collectively evaluated for impairment	211,168,000	197,636,000	178,091,000
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	994,000	790,000	771,000
Provision for loan losses	113,000	267,000	135,000
Losses charged off	(234,000)	(64,000)	(140,000)
Recoveries	1,000	1,000	24,000
Balance, end of period	874,000	994,000	790,000
Individually evaluated for impairment	6,000	0	0
Collectively evaluated for impairment	868,000	994,000	790,000
Ending balance	366,823,000	232,348,000	184,661,000
Individually evaluated for impairment	1,752,000	0	0
Collectively evaluated for impairment	$ 360,825,000	232,348,000	184,661,000
1-4 Family residential properties
Financing Receivable, Impaired [Line Items]
Period When Loans Are Charged Down	180 days
Consumer loans
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	$ 642,000	386,000	377,000
Provision for loan losses	501,000	633,000	167,000
Losses charged off	(664,000)	(553,000)	(311,000)
Recoveries	214,000	176,000	153,000
Balance, end of period	693,000	642,000	386,000
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	693,000	642,000	386,000
Ending balance	41,857,000	43,739,000	15,102,000
Individually evaluated for impairment	213,000	0	0
Collectively evaluated for impairment	41,644,000	43,739,000	15,102,000
Unallocated [Member]
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	224,000	232,000	922,000
Provision for loan losses	(188,000)	(8,000)	(690,000)
Losses charged off	0	0	0
Recoveries	0	0	0
Balance, end of period	36,000	224,000	232,000
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	36,000	224,000	232,000
Ending balance	0	0	0
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	0	$ 0	$ 0
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses	14,000
Financing Receivable, Net	8,086,000
Receivables Acquired with Deteriorated Credit Quality [Member] \| Commercial/Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses	14,000
Financing Receivable, Net	3,840,000
Receivables Acquired with Deteriorated Credit Quality [Member] \| Agriculture/Agricultural Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses	0
Financing Receivable, Net	0
Receivables Acquired with Deteriorated Credit Quality [Member] \| Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses	0
Financing Receivable, Net	4,246,000
Receivables Acquired with Deteriorated Credit Quality [Member] \| Consumer loans
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses	0
Financing Receivable, Net	0
Receivables Acquired with Deteriorated Credit Quality [Member] \| Unallocated [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses	0
Financing Receivable, Net	$ 0

Amount net of deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

No definition available.