Allowance for Loan Losses and Impaired Loans (Credit Risk Profile by Internally Assigned Grades) (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Jul. 01, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	$ 408,566	$ 402,652	$ 241,216
Farmland
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	34,577		31,512
Commercial mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	112,359		52,463
Commercial & agricultural
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	49,276		12,782
Real Estate Secured | 1-4 residential construction
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	4,260		3,268
Real Estate Secured | Land development & other land
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	15,960		11,225
Real Estate Secured | Farmland
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	34,577		31,512
Real Estate Secured | 1-4 residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	134,993		97,880
Real Estate Secured | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	23,672		12,202
Real Estate Secured | Home equity and second mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	23,697		14,902
Real Estate Secured | Commercial mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	112,359		52,463
Non-Real Estate Secured | Commercial & agricultural
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	49,276		12,782
Non-Real Estate Secured | Civic organizations
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	3,286		107
Non-Real Estate Secured | Consumer-auto
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	1,358		1,003
Non-Real Estate Secured | Consumer-other
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	5,128		3,872
Pass
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	353,453		211,452
Pass | Real Estate Secured | 1-4 residential construction
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	4,140		3,268
Pass | Real Estate Secured | Land development & other land
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	13,977		9,555
Pass | Real Estate Secured | Farmland
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	23,312		23,909
Pass | Real Estate Secured | 1-4 residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	121,618		86,360
Pass | Real Estate Secured | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	22,345		11,991
Pass | Real Estate Secured | Home equity and second mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	22,327		13,425
Pass | Real Estate Secured | Commercial mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	94,213		46,084
Pass | Non-Real Estate Secured | Commercial & agricultural
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	41,913		12,000
Pass | Non-Real Estate Secured | Civic organizations
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	3,286		107
Pass | Non-Real Estate Secured | Consumer-auto
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	1,335		957
Pass | Non-Real Estate Secured | Consumer-other
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	4,987		3,796
Watch
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	33,722		24,435
Watch | Real Estate Secured | Land development & other land
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	854		418
Watch | Real Estate Secured | Farmland
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	5,235		5,731
Watch | Real Estate Secured | 1-4 residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	11,268		9,887
Watch | Real Estate Secured | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	1,327		211
Watch | Real Estate Secured | Home equity and second mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	1,254		1,266
Watch | Real Estate Secured | Commercial mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	9,426		6,018
Watch | Non-Real Estate Secured | Commercial & agricultural
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	4,230		782
Watch | Non-Real Estate Secured | Consumer-auto
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	23		46
Watch | Non-Real Estate Secured | Consumer-other
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	105		76
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	4,128		235
Special Mention | Real Estate Secured | 1-4 residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans			29
Special Mention | Real Estate Secured | Commercial mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	2,567		206
Special Mention | Non-Real Estate Secured | Commercial & agricultural
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	1,561
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	17,263		5,094
Substandard | Real Estate Secured | 1-4 residential construction
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	120
Substandard | Real Estate Secured | Land development & other land
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	1,129		1,252
Substandard | Real Estate Secured | Farmland
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	6,030		1,872
Substandard | Real Estate Secured | 1-4 residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	2,107		1,604
Substandard | Real Estate Secured | Home equity and second mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	116		211
Substandard | Real Estate Secured | Commercial mortgage
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	6,153		$ 155
Substandard | Non-Real Estate Secured | Commercial & agricultural
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	1,572
Substandard | Non-Real Estate Secured | Consumer-other
Financing Receivable, Recorded Investment [Line Items]
Total of outstanding loans	$ 36