CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock and Additional Paid-in Capital ATM offering	Common Stock and Additional Paid-in Capital	Accumulated Deficit	ATM offering	Total
Balance at Dec. 31, 2018		$ 1,457,422	$ (971,476)		$ 485,946
Balance (in shares) at Dec. 31, 2018		344,560,000
Increase (Decrease) in Shareholders' Equity
Stock issued during the period				1,010,545
Balance at Mar. 31, 2019		$ 1,479,809	(981,612)		498,197
Balance (in shares) at Mar. 31, 2019		359,986,000
Balance at Dec. 31, 2018		$ 1,457,422	(971,476)		485,946
Balance (in shares) at Dec. 31, 2018		344,560,000
Increase (Decrease) in Shareholders' Equity
Stock-based compensation		$ 197			197
Exercise of stock options		$ 260			$ 260
Exercise of stock options (in shares)		258,000			257,500
Units issued in connection with registered direct offering , net of share issue costs		$ 22,910			$ 22,910
Units issued in connection with registered direct offering , net of share issue costs (in shares)		16,129,000
Stock issued during the period	$ 1,851			$ 1,851
Stock issued during the period	1,010,000
Net loss			(23,150)		(23,150)
Balance at Jun. 30, 2019		$ 1,482,640	(994,626)		488,014
Balance (in shares) at Jun. 30, 2019		361,957,000
Balance at Mar. 31, 2019		$ 1,479,809	(981,612)		498,197
Balance (in shares) at Mar. 31, 2019		359,986,000
Increase (Decrease) in Shareholders' Equity
Stock-based compensation		$ 136			136
Exercise of stock options		$ 37			37
Exercise of stock options (in shares)		36,000
Units issued in connection with registered direct offering , net of share issue costs		$ 2,658			2,658
Units issued in connection with registered direct offering , net of share issue costs (in shares)		1,935,000
Net loss			(13,014)		(13,014)
Balance at Jun. 30, 2019		$ 1,482,640	(994,626)		488,014
Balance (in shares) at Jun. 30, 2019		361,957,000
Balance at Dec. 31, 2019		$ 1,530,702	(1,031,223)		499,479
Balance (in shares) at Dec. 31, 2019		400,339,000
Increase (Decrease) in Shareholders' Equity
Stock-based compensation		$ 302			302
Exercise of stock options		$ 61			$ 61
Exercise of stock options (in shares)		60,000			60,000
Shares issued for debt refinancing		$ 1,875			$ 1,875
Shares issued for debt refinancing (in shares)		2,092,000
Net loss			(119,005)		(119,005)
Balance at Jun. 30, 2020		$ 1,532,940	(1,150,228)		382,712
Balance (in shares) at Jun. 30, 2020		402,491,000
Balance at Mar. 31, 2020		$ 1,530,852	(1,130,414)		400,438
Balance (in shares) at Mar. 31, 2020		400,399,000
Increase (Decrease) in Shareholders' Equity
Stock-based compensation		$ 213			213
Shares issued for debt refinancing		$ 1,875			1,875
Shares issued for debt refinancing (in shares)		2,092,000
Net loss			(19,814)		(19,814)
Balance at Jun. 30, 2020		$ 1,532,940	$ (1,150,228)		$ 382,712
Balance (in shares) at Jun. 30, 2020		402,491,000