Derivative Instruments - Additional Information (Detail) - USD ($)		9 Months Ended
	May 03, 2011	Sep. 30, 2017	Dec. 31, 2016
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Term of interest rate swap agreement executed	5 years
Interest rate swap inception date	May 03, 2011
Value of subordinated note hedged	$ 10,000,000
Interest rate swap effective date	Sep. 15, 2013
Interest rate		The interest rate swap involves the receipt of variable-rate amounts in exchange for fixed-rate payments from September 15, 2013 to September 15, 2018 without exchange of the underlying notional amount.
Derivatives designated as fair value hedges		$ 0	$ 0
Accumulated other comprehensive loss estimated		270,000
Collateral amount for counterparty interest rate swap		$ 1,400,000	1,400,000
LIBOR Plus 155 Basis Points [Member]
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Variable rate on the subordinated debt on effective date in case of interest rate swap		LIBOR plus 155 basis points
Variable interest rate on subordinate debt		2.87%
4.02% Fixed Rate Plus 155 Basis Points [Member]
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Variable rate on the subordinated debt on effective date in case of interest rate swap		4.02% fixed rate plus 155 basis points
Interest rate being paid by the corporation		5.57%
Interest Rate Swaps [Member]
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative basis spread on variable rate		1.55%
Derivative fixed interest rate rate basis		4.02%
Cash collateral pledged		$ 750,000	$ 750,000