Liability Related to Sale of Future Royalties (Tables)

9 Months Ended

Sep. 30, 2020

Debt Disclosure [Abstract]

Schedule of liability for sale of future royalties

The following table shows the activity within the liability related to sales of future royalties account for the nine months ended September 30, 2020 and 2019, respectively, related to the 2018 and 2020 RPI Funding Agreements.

	Nine Months Ended September 30,
	2020		2019
Liability related to sale of future royalties - beginning balance	$	144,111	$	117,515
Additional liability related to the 2020 RPI Funding Agreement, net of issuance costs	147,476		—
Royalty revenues payable to RPI	(667)		—
Non-cash interest expense on liability related to sale of future royalties	31,950		19,284
Liability related to sale of future royalties - ending balance	$	322,870	$	136,799