Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2000 Branch
Significant Accounting Policies [Line Items]
Interest-Bearing Deposits in Banks, maturity period	1 year
Secured borrowings maturity period under repurchase agreements	1 year
Personal loans charged off period no later than period	180 days
Percentage of excess loan balance for watch category	90.00%
Impaired loans measurement	Impaired loans measured for impairment generally include (1) non-accruing Special mention, Substandard and Doubtful loans in excess of $250,000; (2) Substandard and Doubtful loans in excess of $500,000; (3) Special Mention loans in excess of $500,000 if any of the loans in the relationship are more than 30 days past due or if the borrower has filed for bankruptcy; and (4) all TDRs.
Loan Receivables	$ 161,033,000	$ 151,305,000
Number of branches purchased during the years 1994 through 2000 | Branch			5
Deferred tax assets valuation allowance	0
Advertising expense	197,000	213,000
Unrealized gains adjustment, net of tax	(627,000)	62,000
Unrealized market gain included in accumulated other comprehensive income, tax	(175,000)	46,000
Certificates of Deposit
Significant Accounting Policies [Line Items]
Unrealized gains adjustment, net of tax		31,000
Unrealized market gain included in accumulated other comprehensive income, tax		20,000
Special Mention
Significant Accounting Policies [Line Items]
Loan Receivables	$ 2,030,000	$ 3,954,000
Loan due days	30 days
Residential First Mortgages
Significant Accounting Policies [Line Items]
Minimum balance in order to assign a risk rating grade	$ 1,000,000
Consumer and Other Loans
Significant Accounting Policies [Line Items]
Minimum balance in order to assign a risk rating grade	$ 250,000
Minimum
Significant Accounting Policies [Line Items]
Number of days past due for a loan to remain on accrual status	90 days
Real estate properties acquired through, or in lieu of, loan foreclosure, valuation period	2 years
Minimum | Building
Significant Accounting Policies [Line Items]
Estimated useful lives	10 years
Minimum | Furniture and Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Minimum | Non-accruing Special mention, Substandard and Doubtful loans
Significant Accounting Policies [Line Items]
Loan Receivables	$ 250,000
Minimum | Substandard and Doubtful loans
Significant Accounting Policies [Line Items]
Loan Receivables	500,000
Minimum | Special Mention
Significant Accounting Policies [Line Items]
Loan Receivables	$ 500,000
Maximum | Building
Significant Accounting Policies [Line Items]
Estimated useful lives	40 years
Maximum | Furniture and Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives	10 years