Fair Value Measurements - Schedule of Balances of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Securities available for sale:
Securities available-for-sale	$ 52,563	$ 54,090	[1]
Mortgage servicing rights	590	658	[1]
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	2,689	2,806
Corporate Bonds
Securities available for sale:
Securities available-for-sale	7,003	3,945
US Government Agencies
Securities available for sale:
Securities available-for-sale	25,677	21,288
State and Municipal Obligations
Securities available for sale:
Securities available-for-sale	19,883	28,857
Cash and Cash Equivalents
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	3	3
Fixed Income Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,071	1,119
Equity Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,615	1,684
Fair Value, Inputs, Level 1
Securities available for sale:
Securities available-for-sale	1,597	1,216
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	2,689	2,806
Fair Value, Inputs, Level 1 | US Government Agencies
Securities available for sale:
Securities available-for-sale	1,597	1,216
Fair Value, Inputs, Level 1 | Cash and Cash Equivalents
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	3	3
Fair Value, Inputs, Level 1 | Fixed Income Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,071	1,119
Fair Value, Inputs, Level 1 | Equity Funds
Defined benefit plan assets:
Defined Benefit Plan Fair Value Of Plan Assets	1,615	1,684
Fair Value, Inputs, Level 2
Securities available for sale:
Securities available-for-sale	45,463	48,929
Fair Value, Inputs, Level 2 | Corporate Bonds
Securities available for sale:
Securities available-for-sale	1,500
Fair Value, Inputs, Level 2 | US Government Agencies
Securities available for sale:
Securities available-for-sale	24,080	20,072
Fair Value, Inputs, Level 2 | State and Municipal Obligations
Securities available for sale:
Securities available-for-sale	19,883	28,857
Fair Value, Inputs, Level 3
Securities available for sale:
Securities available-for-sale	5,503	3,945
Mortgage servicing rights	590	658
Fair Value, Inputs, Level 3 | Corporate Bonds
Securities available for sale:
Securities available-for-sale	$ 5,503	$ 3,945

[1] Derived from Audited December 31, 2015 Financial Statements