FAIR VALUES OF FINANCIAL INSTRUMENTS - Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Derivative financial instruments	$ 184	$ 8
Fair Value, Measurements, Recurring [Member]
Assets:
Assets estimated fair value	227,746	163,059
Derivative financial instruments	184	8
Fair Value, Measurements, Recurring [Member] | Obligations of other U. S. government agencies [Member]
Assets:
Assets estimated fair value	55,496	29,490
Fair Value, Measurements, Recurring [Member] | Obligations of state and political subdivisions [Member]
Assets:
Assets estimated fair value	35,531	27,855
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Assets estimated fair value	16,558	14,968
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities [Member]
Assets:
Assets estimated fair value	115,789	87,588
Fair Value, Measurements, Recurring [Member] | Commercial mortgage-backed securities [Member]
Assets:
Assets estimated fair value	3,177	2,444
Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Assets estimated fair value	1,011	706
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Assets estimated fair value	1,011	706
Derivative financial instruments	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Obligations of other U. S. government agencies [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Obligations of state and political subdivisions [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Residential mortgage-backed securities [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Commercial mortgage-backed securities [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity securities [Member]
Assets:
Assets estimated fair value	1,011	706
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets estimated fair value	205,809	144,073
Derivative financial instruments	184	8
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Obligations of other U. S. government agencies [Member]
Assets:
Assets estimated fair value	55,496	29,490
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Obligations of state and political subdivisions [Member]
Assets:
Assets estimated fair value	15,933	10,199
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Assets estimated fair value	15,230	14,344
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Residential mortgage-backed securities [Member]
Assets:
Assets estimated fair value	115,789	87,588
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Commercial mortgage-backed securities [Member]
Assets:
Assets estimated fair value	3,177	2,444
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Equity securities [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Assets estimated fair value	20,926	18,280
Derivative financial instruments	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Obligations of other U. S. government agencies [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Obligations of state and political subdivisions [Member]
Assets:
Assets estimated fair value	19,598	17,656
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Assets:
Assets estimated fair value	1,328	624
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Residential mortgage-backed securities [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Commercial mortgage-backed securities [Member]
Assets:
Assets estimated fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity securities [Member]
Assets:
Assets estimated fair value	$ 0	$ 0