Restructuring - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Restructuring Cost [Line Items]
Restructuring charges		$ 472,000
Non-cash stock-based compensation expense for modification of exercise period of vested stock options		2,456,000	$ 2,163,000	$ 1,961,000
Research and Development Expense [Member]
Restructuring Cost [Line Items]
Non-cash stock-based compensation expense for modification of exercise period of vested stock options		$ 1,109,000	$ 702,000	$ 676,000
U.K. [Member]
Restructuring Cost [Line Items]
Extended lease term expiration date		Nov. 30, 2016
Discretionary termination benefits		$ 273,000
Other restructuring costs		199,000
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] | Research and Development Expense [Member]
Restructuring Cost [Line Items]
Restructuring charges		$ 472,000