Warrants - Schedule of Outstanding Warrants to Purchase the Company's Common Stock (Detail) - $ / shares	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	956,552	956,552
Warrants Issued in Two Thousand and Fifteen [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Warrant or Right, Reason for Issuance, Description	Common Stock
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 5.25
Warrants and Rights Outstanding, Maturity Date	Jan. 30, 2025
Class of Warrant or Right, Outstanding	7,616	7,616
Warrants Issued in Two Thousand and Eighteen with Convertible Notes [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Warrant or Right, Reason for Issuance, Description	Common Stock
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.10		$ 0.10
Warrants and Rights Outstanding, Maturity Date	Jun. 07, 2028
Class of Warrant or Right, Outstanding	501,946	501,946
Warrants Issued in Two Thousand and Eighteen Term Loan [Member] | Redeemable Convertible Series D Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Warrant or Right, Reason for Issuance, Description	Series D convertible preferred
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 16.67		$ 16.667
Warrants and Rights Outstanding, Maturity Date	Jul. 31, 2028
Class of Warrant or Right, Outstanding	26,998	26,998
Warrants Issued in with Two Thousand and Nineteen Credit Agreement [Member] | Redeemable Convertible Series D Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Warrant or Right, Reason for Issuance, Description	Series D convertible preferred
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 16.67	$ 16.667
Warrants and Rights Outstanding, Maturity Date	May 20, 2029
Class of Warrant or Right, Outstanding	419,992	419,992