Fair Value Measurements - Schedule of Balances of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Securities available for sale:
Securities available-for-sale	$ 51,173	$ 54,090
Mortgage servicing rights	671	658
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	2,690	2,806
Corporate Bonds
Securities available for sale:
Securities available-for-sale	7,704	3,945
US Government Agencies
Securities available for sale:
Securities available-for-sale	25,313	21,288
State and Municipal Obligations
Securities available for sale:
Securities available-for-sale	18,156	28,857
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	1,041	1,119
Equity Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,649	1,684
Fair Value, Inputs, Level 1
Securities available for sale:
Securities available-for-sale		1,216
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	2,690	2,806
Fair Value, Inputs, Level 1 | US Government Agencies
Securities available for sale:
Securities available-for-sale		1,216
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	1,041	1,119
Fair Value, Inputs, Level 1 | Equity Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,649	1,684
Fair Value, Inputs, Level 2
Securities available for sale:
Securities available-for-sale	43,469	48,929
Fair Value, Inputs, Level 2 | US Government Agencies
Securities available for sale:
Securities available-for-sale	25,313	20,072
Fair Value, Inputs, Level 2 | State and Municipal Obligations
Securities available for sale:
Securities available-for-sale	18,156	28,857
Fair Value, Inputs, Level 3
Securities available for sale:
Securities available-for-sale	7,704	3,945
Mortgage servicing rights	671	658
Fair Value, Inputs, Level 3 | Corporate Bonds
Securities available for sale:
Securities available-for-sale	$ 7,704	$ 3,945