Fair Value Measurements - Schedule of Balances of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Securities available for sale:
Securities available-for-sale	$ 49,826	$ 51,173
Mortgage servicing rights	692	671
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	2,623	2,690
Corporate Bonds
Securities available for sale:
Securities available-for-sale	6,715	7,704
US Government Agencies
Securities available for sale:
Securities available-for-sale	24,235	25,313
State and Municipal Obligations
Securities available for sale:
Securities available-for-sale	18,876	18,156
Cash and Cash Equivalents
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	3
Fixed Income Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,043	1,041
Equity Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,577	1,649
Fair Value, Inputs, Level 1
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	2,623	2,690
Fair Value, Inputs, Level 1 | Cash and Cash Equivalents
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	3
Fair Value, Inputs, Level 1 | Fixed Income Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,043	1,041
Fair Value, Inputs, Level 1 | Equity Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,577	1,649
Fair Value, Inputs, Level 2
Securities available for sale:
Securities available-for-sale	43,111	43,469
Fair Value, Inputs, Level 2 | US Government Agencies
Securities available for sale:
Securities available-for-sale	24,235	25,313
Fair Value, Inputs, Level 2 | State and Municipal Obligations
Securities available for sale:
Securities available-for-sale	18,876	18,156
Fair Value, Inputs, Level 3
Securities available for sale:
Securities available-for-sale	6,715	7,704
Mortgage servicing rights	692	671
Fair Value, Inputs, Level 3 | Corporate Bonds
Securities available for sale:
Securities available-for-sale	$ 6,715	$ 7,704