CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Allowances for doubtful accounts	$ 0	$ 0
Property and equipment, accumulated depreciation	$ 8,907	$ 7,925
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	250,000,000	250,000,000,000
Common stock, shares issued (in shares)	213,929,505	212,529,313
Common stock, shares outstanding (in shares)	213,809,884	212,409,692
Treasury stock, shares (in shares)	119,621	119,621
Convertible Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0