Summary of Significant Accounting Policies - Reverse Stock Split (Details)		9 Months Ended
	Dec. 17, 2020 $ / shares	Sep. 30, 2021 $ / shares shares	Dec. 31, 2020 $ / shares
Class of Stock [Line Items]
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01
Common Stock [Member]
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.01
Stock split, conversion ratio	0.2
Stock issued during period, shares, fractional shares settled in cash (in shares) | shares		0