Derivative Instruments - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Oct. 31, 2008
Derivative Instruments, Gain (Loss) [Line Items]
Hedging gains or losses, fair value	$ 0	$ 0
Duration of interest rate swap agreement	7 years
Interest rate swap amount			$ 10,000,000
Fixed rate of interest rate swap agreement to be paid	7.27%
Interest rate to be received under swap agreement	Three-month London Interbank Lending Rate (LIBOR) plus 3.10%
LIBOR	3.10%
Cost of termination of cash flow hedge	$ 99,000	$ 390,000
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate swap agreement expiry date	Oct. 08, 2015