Stockholders' Equity	3 Months Ended
Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	NOTE 6. STOCKHOLDERS’ EQUITY At December 31, 2018, the Company had a total of 150,000,000 shares of capital stock authorized for issuance, consisting of 145,000,000 shares of Common Stock, par value $0.001 per share, and 5,000,000 shares of Preferred Stock, par value $0.001 per share. At December 31, 2018, 92,591,457 shares of Common Stock were outstanding. At December 31, 2018, 7,954,283 shares of Common Stock were reserved for issuance upon exercise of options and vesting of restricted stock units granted or available for grant under Arrowhead’s 2004 Equity Incentive Plan and 2013 Incentive Plan, as well as for inducement grants made to new employees. In October 2018 the Company sold 3,260,869 shares of Common Stock to JJDC at a price of $23.00 per share as part of the JJDC Stock Purchase Agreement discussed further in Note 2 above. The Company received proceeds of $75.0 million. The portion of these proceeds that were deemed to be a premium were recorded as deferred revenue as discussed further in Note 2 above.

Stockholders' Equity

3 Months Ended

Dec. 31, 2018

NOTE 6. STOCKHOLDERS’ EQUITY

At December 31, 2018, the Company had a total of 150,000,000 shares of capital stock authorized for issuance, consisting of 145,000,000 shares of Common Stock, par value $0.001 per share, and 5,000,000 shares of Preferred Stock, par value $0.001 per share.

At December 31, 2018, 92,591,457 shares of Common Stock were outstanding. At December 31, 2018, 7,954,283 shares of Common Stock were reserved for issuance upon exercise of options and vesting of restricted stock units granted or available for grant under Arrowhead’s 2004 Equity Incentive Plan and 2013 Incentive Plan, as well as for inducement grants made to new employees.

In October 2018 the Company sold 3,260,869 shares of Common Stock to JJDC at a price of $23.00 per share as part of the JJDC Stock Purchase Agreement discussed further in Note 2 above. The Company received proceeds of $75.0 million. The portion of these proceeds that were deemed to be a premium were recorded as deferred revenue as discussed further in Note 2 above.