Redeemable Convertible Preferred Stock - Additional Information (Details)				1 Months Ended											9 Months Ended
	May 22, 2020	Dec. 19, 2019	Jul. 10, 2018	Feb. 29, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Nov. 30, 2018 USD ($) $ / shares shares	Jul. 31, 2018 USD ($) $ / shares shares	Mar. 31, 2018 USD ($) $ / shares shares	Jan. 31, 2018 USD ($) $ / shares shares	Jul. 31, 2017 USD ($) $ / shares shares	Feb. 28, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($) $ / shares shares	Apr. 30, 2016 USD ($) $ / shares shares	Aug. 31, 2015 USD ($) Tranche $ / shares shares	Sep. 30, 2020 Member $ / shares shares	Mar. 31, 2020 shares	Sep. 30, 2019 shares	Jun. 30, 2019 shares	Mar. 31, 2019 shares	Dec. 31, 2018 shares
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding					0										0
Redeemable convertible preferred stock, shares issued					0										0
Redeemable convertible preferred stock, par value | $ / shares					$ 0.0001										$ 0.0001
Redeemable convertible preferred stock, shares authorized					0										10,000,000
Preferred stock, voting rights description															Each holder of shares of Preferred Stock were entitled to the number of votes equal to the number of shares of common stock into which such shares could have been converted and had voting rights and powers equal to the voting rights and powers of the common stock, and except as provided by law or by other provisions of the Company’s Certificate of Incorporation, as amended, could have voted together with the common stock as a single class on an as-converted basis on all matters as to which holders of common stock have the right to vote.
Convertible preferred stock, terms of conversion															Shares of the Preferred Stock were convertible at any time at the option of the holder into such number of shares as is determined by dividing the original issuance price by the conversion price in effect at the time.
Reverse stock split, conversion ratio	0.13986014														0.1399
Series B Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Preferred stock redemption terms															All outstanding shares of Preferred Stock shall be redeemed by the Company at a price equal to the original issuance price per share, plus any accrued and unpaid dividends, whether or not declared, together with any other dividends declared but unpaid in three annual installments commencing not more than sixty (60) days after receipt by the Company at any time on or after five years from the Series B Preferred original issuance date, July 10, 2018, a written notice from the holders of a majority of the shares of Preferred Stock.
Series C Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Preferred stock redemption terms															All outstanding shares of Preferred Stock shall be redeemed by the Company at a price equal to the original issuance price per share, plus any dividends declared but unpaid, in three annual installments commencing not more than sixty (60) days after receipt by the Company at any time on or after five years from the Series C Preferred original issuance date, December 19, 2019, a written notice from the holders of a majority of the shares of Preferred Stock.
Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding															0
Series A Preferred Stock
Temporary Equity [Line Items]
Preferred stock dividend rate														8.00%
Preferred stock shares redemption														6,500,000
Series A Preferred Stock | Series A Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Number of tranches | Tranche														3
Redeemable convertible preferred stock, shares issued														6,500,000
Redeemable convertible preferred stock, par value | $ / shares														$ 1.00
Cash proceeds from preferred stock | $														$ 6,400,000
Outstanding principal and accrued interest | $														100,000
Series A Preferred Stock | Series A Preferred Stock Purchase Agreement | First Tranche
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares issued												5,000,000	5,000,000
Redeemable convertible preferred stock, par value | $ / shares												$ 1.00	$ 1.00
Cash proceeds from preferred stock | $												$ 5,000,000	$ 5,000,000
Series A Preferred Stock | Series A Preferred Stock Purchase Agreement | Second Tranche
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares issued											8,000,000
Redeemable convertible preferred stock, par value | $ / shares											$ 1.00
Cash proceeds from preferred stock | $											$ 8,000,000
Series A Preferred Stock | Series A Preferred Stock Purchase Agreement | Third Tranche
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares issued								11,000,000	8,500,000	12,000,000
Redeemable convertible preferred stock, par value | $ / shares								$ 1.00	$ 1.00	$ 1.00
Cash proceeds from preferred stock | $								$ 11,000,000	$ 8,500,000	$ 12,000,000
Series A Preferred Stock | Maximum | Series A Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Preferred stock, purchase amount | $														$ 45,000,000
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding					49,501,221										0	49,501,221	49,501,221	49,501,221	49,501,221	49,501,221
Redeemable convertible preferred stock, shares issued					49,501,221										0
Redeemable convertible preferred stock, par value | $ / shares					$ 0.0001										$ 0.0001
Redeemable convertible preferred stock, shares authorized					49,501,221										0
Number of members of board of directors | Member															1
Preferred stock conversion price per share | $ / shares															$ 9.843405
Preferred stock liquidation price per share | $ / shares															$ 1.3767
Series B Redeemable Convertible Preferred Stock | Series B Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares issued						4,400,000	45,100,000
Redeemable convertible preferred stock, par value | $ / shares						$ 1.3767	$ 1.3767
Cash proceeds from preferred stock | $						$ 6,000,000	$ 62,100,000
Series B Redeemable Convertible Preferred Stock | Maximum | Series B Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Preferred stock, purchase amount | $							$ 70,000,000
Series B Redeemable Convertible Preferred Stock | Minimum [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding															12,500,000
Series C Preferred Stock [Member] | Series C Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares issued				28,500,000	26,400,000
Redeemable convertible preferred stock, par value | $ / shares				$ 1.83	$ 1.83
Cash proceeds from preferred stock | $				$ 52,200,000	$ 48,200,000
Preferred stock, shares issuance costs | $				$ 200,000
Series C Preferred Stock [Member] | Series C Preferred Stock Purchase Agreement | Novartis
Temporary Equity [Line Items]
Redeemable convertible preferred stock, par value | $ / shares					$ 1.83
Cash proceeds from preferred stock | $					$ 20,000,000
Redeemable convertible preferred stock, shares authorized					10,900,000
Percentage of outstanding shares of common stock on fully diluted basis					7.40%										6.10%
Series C Preferred Stock [Member] | Maximum | Series C Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Preferred stock, purchase amount | $					$ 80,500,000
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding					56,000,000										0	56,000,000	56,000,000	56,000,000	56,000,000	56,000,000
Redeemable convertible preferred stock, shares issued					56,000,000										0
Redeemable convertible preferred stock, par value | $ / shares					$ 0.0001										$ 0.0001
Redeemable convertible preferred stock, shares authorized					56,000,000										0
Number of members of board of directors | Member															2
Preferred stock conversion price per share | $ / shares															$ 7.15
Preferred stock liquidation price per share | $ / shares															$ 1.00
Common Stock
Temporary Equity [Line Items]
Number of members of board of directors | Member															1
Series C Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding					26,360,745										0	54,888,058
Redeemable convertible preferred stock, shares issued					26,360,745										0
Redeemable convertible preferred stock, par value | $ / shares					$ 0.0001										$ 0.0001
Redeemable convertible preferred stock, shares authorized					44,000,000										0
Preferred stock conversion price per share | $ / shares															$ 13.0845
Preferred stock liquidation price per share | $ / shares															$ 1.83
Series A and Series B Preferred | Series B Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Preferred stock dividend rate			8.00%
Series A, Series B and Series C Preferred | Series C Preferred Stock Purchase Agreement
Temporary Equity [Line Items]
Preferred stock dividend rate		8.00%