Equity Transactions and Share-based Compensation - Schedule of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Total share-based compensation expense	$ 3,112	$ 1,391	$ 5,696	$ 2,717
Research and development expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Total share-based compensation expense	1,765	725	3,142	1,465
General and administrative expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Total share-based compensation expense	$ 1,347	$ 666	$ 2,554	$ 1,252