Basis of Presentation and Significant Accounting Policies - Computation of Net Loss per Common Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Computation of Net Loss per Common Share
Options outstanding to purchase common stock, shares issuable under the employee stock purchase plan, and unvested restricted stock/units at end of period	29,528	21,681	29,528	21,681
Common stock equivalents under treasury stock method for options, shares issuable under the employee stock purchase plan, and unvested restricted stock/units	958	2,772	1,306	3,138