Income Taxes - Summary of Effective Income Tax Rate Reconciliation (Detail)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
At U.S. federal statutory rate	34.00%	34.00%
State taxes, net of federal effect	4.90%	9.00%
Stock compensation	(5.80%)	(1.10%)
Mark-to-market adjustments	0.90%	(0.10%)
Valuation allowance	(23.10%)	(41.10%)
True-up on deferred taxes	(3.00%)
State blended rate change	(5.70%)
Other	(2.20%)	(0.70%)
Effective income tax rate	0.00%	0.00%