Investment Advisory Agreements - Additional Information (Detail)	0 Months Ended	6 Months Ended
	Feb. 28, 2014	Mar. 31, 2015 Funds
Investments Schedule [Abstract]
Number of Hennessy funds to which company provided investment advisory services		16
Notice period for termination of agreement		60 days
Agreement term	2 years
Initial management agreement renewal period	1 year