Revolving Line of Credit - Additional Information (Detail) (Revolving Credit Facility [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2013
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Revolving credit facility period	3 years
Borrowing credit facility		$ 10,000,000
Additional borrowing credit facility		5,000,000
Total credit facility borrowing capacity		15,000,000
Variable interest rate	The LIBOR Rate plus 1.5%
LIBOR Rate plus	1.50%
Annual commitment fee	0.15%
Due date of amounts outstanding under credit facility	Sep. 23, 2016
Amount drawn under credit facility	$ 0