Common and Preferred Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Mar. 31, 2021	Feb. 28, 2018	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Class of Stock [Line Items]
Common stock, shares authorized			400,000,000		400,000,000		400,000,000
Common stock, par value			$ 0.01		$ 0.01		$ 0.01
Undesignated preferred stock, shares authorized			10,000,000		10,000,000		10,000,000
Undesignated preferred stock, par value			$ 0.01		$ 0.01		$ 0.01
Common stock, shares issued			257,276,847		257,276,847		251,477,562
Common stock, shares outstanding			257,276,847		257,276,847		251,477,562
Preferred stock, shares outstanding			0		0		0
Debt issuance amount	$ 230,000
Proceeds from market price stock purchase plan				$ 100	$ 684	$ 106
Market price stock purchase plan				25,000	252,176	25,000
Convertible Promissory Note | Mann Group
Class of Stock [Line Items]
Debt issuance amount			$ 10,000
Capitalized interest into common stock			4,000,000
Common stock issued to pay interest			31,541
Controlled Equity Offering Sales Agreement | Cantor Fitzgerald
Class of Stock [Line Items]
Stock sales agreements date		Feb. 28, 2018
Controlled Equity Offering Sales Agreement | Cantor Fitzgerald | Common Stock | Maximum
Class of Stock [Line Items]
Amount of net proceeds from issuance of securities		$ 50,000
At Market Issuance Sales Agreement
Class of Stock [Line Items]
Sales under sales agreement					$ 0
At Market Issuance Sales Agreement | Cantor Fitzgerald | Common Stock
Class of Stock [Line Items]
Amount of net proceeds from issuance of securities						$ 1,900
Number of shares sold during the period						578,063
At Market Issuance Sales Agreement | Cantor Fitzgerald | Common Stock | Weighted Average
Class of Stock [Line Items]
Exchange price per share				$ 3.26		$ 3.26