Stockholders' Equity - Additional Information (Detail) - $ / shares	Dec. 31, 2020	Sep. 30, 2020
Class Of Stock [Line Items]
Capital stock authorized for issuance	150,000,000
Common stock, shares authorized	145,000,000	145,000,000
Common stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000
Preferred stock, par value	$ 0.001
Common stock, shares outstanding	103,194,240	102,376,000
2004 Equity Incentive Plan, 2013 Equity Incentive Plan, and Inducement Grants
Class Of Stock [Line Items]
Common Stock, Share reserve for issuance	7,635,023