Stock-Based Compensation - Summary of Restricted Stock Activity (Detail) - Restricted Stock Units (RSUs) - $ / shares	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Unvested, beginning of period			510,000
Number of restricted stock units outstanding, granted	0	470,000	705,000	470,000	510,000
Shares, Vested			(267,500)
Shares, Unvested, End of period	947,500		947,500		510,000
Weighted average grant date fair value, beginning balance			$ 14.58
Weighted average grant date fair value, Granted			7.41		$ 14.58
Weighted average grant date fair value, Vested			14.54
Weighted average grant date fair value, ending balance	$ 9.26		$ 9.26		$ 14.58