Fair Value Measurement - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	$ 180,212	$ 184,791
U.S. Agency Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	80,146	84,093
Taxable Municipals Bonds [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	1,273	1,283
Tax Free Municipal Bonds [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	26,668	26,966
Trust Preferred Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	1,980	1,685
Mortgage-Backed Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	70,145	70,764
Fair Value, Measurements, Recurring [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	180,212	184,791
Fair Value, Measurements, Recurring [Member] | U.S. Agency Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	80,146	84,093
Fair Value, Measurements, Recurring [Member] | Taxable Municipals Bonds [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	26,668	1,283
Fair Value, Measurements, Recurring [Member] | Tax Free Municipal Bonds [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	1,273	26,966
Fair Value, Measurements, Recurring [Member] | Trust Preferred Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	1,980	1,685
Fair Value, Measurements, Recurring [Member] | Mortgage-Backed Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	70,145	70,764
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	178,232	183,106
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	178,232	183,106
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Agency Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	80,146	84,093
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Taxable Municipals Bonds [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	26,668	1,283
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Tax Free Municipal Bonds [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	1,273	26,966
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-Backed Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	70,145	70,764
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	1,980	1,685
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	1,980	1,685
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Trust Preferred Securities [Member]
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Securities available for sale	$ 1,980	$ 1,685