Equity Financing (Details) - USD ($)							12 Months Ended
	Nov. 18, 2021	Nov. 16, 2021	Jan. 07, 2021	Jan. 04, 2021	Dec. 06, 2019	Dec. 03, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2019
Subsidiary Sale Of Stock [Line Items]
Aggregate proceeds from issuance of common stock							$ 137,884,000	$ 0	$ 149,559,000
Common Stock
Subsidiary Sale Of Stock [Line Items]
Number of shares issued in transaction		14,375,000		11,856,500		47,782,500
Sale of stock, price (in dollars per share)		$ 5.60		$ 4.85		$ 3.13
Aggregate proceeds from issuance of common stock	$ 75,100,000		$ 53,500,000		$ 138,400,000
Stock issued during period							26,231,500		47,782,500
At The Market Offering Program January 2019 | Maximum
Subsidiary Sale Of Stock [Line Items]
Maximum common stock saleable shares, value										$ 100,000,000
Maximum aggregate offering price										$ 250,000,000
At The Market Offering Program January 2019 | Common Stock
Subsidiary Sale Of Stock [Line Items]
Stock issued during period								0	0