Loans and Allowance for Loan and Lease Losses - TDRs (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan	Dec. 31, 2014 USD ($) loan
Troubled debt restructurings
Accruing loans that were classified as TDRs	$ 9,250	$ 10,056
Non-Accruing loans that were classified as TDRs	5,794	6,203
Total loans classified as TDRs	$ 15,044	$ 16,259
Number of TDRs | loan		44	33
Pre-Modification Outstanding Recorded Investment		$ 9,873	$ 4,436
Post-Modification Outstanding Recorded Investment		$ 9,873
Troubled Debt Restructurings That Subsequently Defaulted
Number of TDRs | loan	1	1
Commitments to lend to borrowers with restructured obligations	$ 400
Minimum
Troubled debt restructurings
Period of maturity date extensions granted	6 months
Maximum
Troubled debt restructurings
Period of maturity date extensions granted	10 years
Non-PCI Loans
Troubled debt restructurings
Accruing loans that were classified as TDRs	$ 7,926	$ 8,619
Non-Accruing loans that were classified as TDRs	5,741	6,091
Total loans classified as TDRs	$ 13,667	$ 14,710
Number of TDRs | loan	21	37	29
Pre-Modification Outstanding Recorded Investment	$ 3,957	$ 8,333	$ 4,029
Post-Modification Outstanding Recorded Investment	$ 3,957	$ 8,333	$ 4,029
Troubled Debt Restructurings That Subsequently Defaulted
Number of TDRs | loan	2	1	2
Recorded Investment	$ 83	$ 18	$ 233
Non-PCI Loans | Agriculture
Troubled debt restructurings
Number of TDRs | loan	1
Pre-Modification Outstanding Recorded Investment	$ 10
Post-Modification Outstanding Recorded Investment	10
Non-PCI Loans | Real Estate Secured | Commercial
Troubled debt restructurings
Accruing loans that were classified as TDRs	2,202	2,395
Non-Accruing loans that were classified as TDRs	107	435
Total loans classified as TDRs	2,309	$ 2,830
Number of TDRs | loan		6	2
Pre-Modification Outstanding Recorded Investment		$ 1,102	$ 312
Post-Modification Outstanding Recorded Investment		1,102	$ 312
Non-PCI Loans | Real Estate Secured | Farmland
Troubled debt restructurings
Accruing loans that were classified as TDRs	375	613
Non-Accruing loans that were classified as TDRs		81
Total loans classified as TDRs	375	$ 694
Number of TDRs | loan		3
Pre-Modification Outstanding Recorded Investment		$ 814
Post-Modification Outstanding Recorded Investment		814
Non-PCI Loans | Real Estate Secured | Residential 1 to 4 family
Troubled debt restructurings
Accruing loans that were classified as TDRs	250	504
Non-Accruing loans that were classified as TDRs	72	82
Total loans classified as TDRs	$ 322	$ 586
Number of TDRs | loan	1	4	1
Pre-Modification Outstanding Recorded Investment	$ 222	$ 753	$ 39
Post-Modification Outstanding Recorded Investment	222	753	$ 39
Non-PCI Loans | Real Estate Secured | Construction and land
Troubled debt restructurings
Accruing loans that were classified as TDRs	703	1,171
Non-Accruing loans that were classified as TDRs	3,154	3,968
Total loans classified as TDRs	3,857	$ 5,139
Number of TDRs | loan		1	4
Pre-Modification Outstanding Recorded Investment		$ 97	$ 811
Post-Modification Outstanding Recorded Investment		97	$ 811
Non-PCI Loans | Commercial | Commercial and industrial
Troubled debt restructurings
Accruing loans that were classified as TDRs	3,422	2,698
Non-Accruing loans that were classified as TDRs	2,400	1,515
Total loans classified as TDRs	$ 5,822	$ 4,213
Number of TDRs | loan	19	15	20
Pre-Modification Outstanding Recorded Investment	$ 3,725	$ 3,414	$ 2,132
Post-Modification Outstanding Recorded Investment	3,725	3,414	$ 2,132
Non-PCI Loans | Commercial | Agriculture
Troubled debt restructurings
Accruing loans that were classified as TDRs	925	1,124
Total loans classified as TDRs	925	$ 1,124
Number of TDRs | loan		6	1
Pre-Modification Outstanding Recorded Investment		$ 2,085	$ 662
Post-Modification Outstanding Recorded Investment		2,085	$ 662
Non-PCI Loans | Consumer
Troubled debt restructurings
Accruing loans that were classified as TDRs	49	114
Non-Accruing loans that were classified as TDRs	8	10
Total loans classified as TDRs	57	$ 124
Number of TDRs | loan		2	1
Pre-Modification Outstanding Recorded Investment		$ 68	$ 73
Post-Modification Outstanding Recorded Investment		68	$ 73
PCI loans
Troubled debt restructurings
Accruing loans that were classified as TDRs	1,324	1,437
Non-Accruing loans that were classified as TDRs	53	112
Total loans classified as TDRs	1,377	$ 1,549
Number of TDRs | loan		7	4
Pre-Modification Outstanding Recorded Investment		$ 1,540	$ 407
Post-Modification Outstanding Recorded Investment		1,540	$ 407
PCI loans | Real Estate Secured | Commercial
Troubled debt restructurings
Accruing loans that were classified as TDRs	893	922
Non-Accruing loans that were classified as TDRs	17	46
Total loans classified as TDRs	910	$ 968
Number of TDRs | loan		5	1
Pre-Modification Outstanding Recorded Investment		$ 993	$ 230
Post-Modification Outstanding Recorded Investment		993	$ 230
PCI loans | Real Estate Secured | Construction and land
Troubled debt restructurings
Accruing loans that were classified as TDRs	61	54
Total loans classified as TDRs	61	$ 54
Number of TDRs | loan		1
Pre-Modification Outstanding Recorded Investment		$ 50
Post-Modification Outstanding Recorded Investment		50
PCI loans | Real Estate Secured | Commercial and industrial
Troubled debt restructurings
Accruing loans that were classified as TDRs	370	461
Non-Accruing loans that were classified as TDRs	36	66
Total loans classified as TDRs	$ 406	$ 527
PCI loans | Commercial | Commercial and industrial
Troubled debt restructurings
Number of TDRs | loan		1	3
Pre-Modification Outstanding Recorded Investment		$ 497	$ 177
Post-Modification Outstanding Recorded Investment		$ 497	$ 177