Restructuring - Additional Information (Detail) - USD ($)		3 Months Ended
	Jul. 31, 2016	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2015
Restructuring Cost [Line Items]
Additional restructuring charges			$ 436,000
Non-cash stock-based compensation expense for modification of exercise period of vested stock options			$ 734,000	$ 405,000
U.K. [Member]
Restructuring Cost [Line Items]
Extended lease term expiration date			Nov. 30, 2016
Additional restructuring charges			$ 436,000
Discretionary termination benefits			273,000
Other restructuring costs			$ 163,000
Non-cash stock-based compensation expense for modification of exercise period of vested stock options	$ 99,000
Reduction of stock-based compensation to account for forfeitures of non-vested stock options	$ 133,000
U.K. [Member] | Scenario, Forecast [Member] | Minimum [Member]
Restructuring Cost [Line Items]
Additional restructuring charges		$ 30,000
U.K. [Member] | Scenario, Forecast [Member] | Maximum [Member]
Restructuring Cost [Line Items]
Additional restructuring charges		$ 40,000