Organization, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Adjustment of Carrying Value to Their Estimated Fair Value (Parenthetical) (Details)	Sep. 30, 2019	May 07, 2019
Takeda Warrants | Financing Transactions
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value method, valuation processes percentage	70.00%	40.00%
Takeda Warrants | Income Approach
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value method, valuation processes percentage	30.00%	60.00%
May 2019 Notes | Financing Transactions
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value method, valuation processes percentage	70.00%	40.00%
May 2019 Notes | Income Approach
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value method, valuation processes percentage	30.00%	60.00%