Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balances at Dec. 31, 2017	$ 814,977	$ 1,856	$ 3,357,345	$ (2,546,743)	$ 2,519
Balances, in shares at Dec. 31, 2017		185,638,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	1,241			1,241
Other comprehensive income (loss)	(278)				(278)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		538,000
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	(1,629)	$ 6	(1,635)
Balances at Mar. 31, 2018	814,311	$ 1,862	3,355,710	(2,542,898)	(363)
Balances, in shares at Mar. 31, 2018		186,176,000
Balances at Dec. 31, 2017	814,977	$ 1,856	3,357,345	(2,546,743)	2,519
Balances, in shares at Dec. 31, 2017		185,638,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	4,171
Other comprehensive income (loss)	(365)
Balances at Jun. 30, 2018	818,771	$ 1,871	3,357,318	(2,539,968)	(450)
Balances, in shares at Jun. 30, 2018		187,074,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new accounting standard	0			2,604	(2,604)
Balances at Mar. 31, 2018	814,311	$ 1,862	3,355,710	(2,542,898)	(363)
Balances, in shares at Mar. 31, 2018		186,176,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	2,930			2,930
Other comprehensive income (loss)	(87)				(87)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		898,000
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	1,617	$ 9	1,608
Balances at Jun. 30, 2018	818,771	$ 1,871	3,357,318	(2,539,968)	(450)
Balances, in shares at Jun. 30, 2018		187,074,000
Balances at Dec. 31, 2018	852,512	$ 2,033	3,443,082	(2,592,544)	(59)
Balances, in shares at Dec. 31, 2018		203,310,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(19,201)			(19,201)
Other comprehensive income (loss)	59				59
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		1,801,000
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	(1,035)	$ 18	(1,053)
Balances at Mar. 31, 2019	832,335	$ 2,051	3,442,029	(2,611,745)	0
Balances, in shares at Mar. 31, 2019		205,111,000
Balances at Dec. 31, 2018	852,512	$ 2,033	3,443,082	(2,592,544)	(59)
Balances, in shares at Dec. 31, 2018		203,310,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(55,965)
Other comprehensive income (loss)	59
Balances at Jun. 30, 2019	846,446	$ 2,219	3,492,736	(2,648,509)	0
Balances, in shares at Jun. 30, 2019		221,859,000
Balances at Mar. 31, 2019	832,335	$ 2,051	3,442,029	(2,611,745)	0
Balances, in shares at Mar. 31, 2019		205,111,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(36,764)
Other comprehensive income (loss)	$ 0
Stock Issued During Period, Shares, New Issues	16,630,444	16,631,000
Stock Issued During Period, Value, New Issues	$ 48,887	$ 166	48,721
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		117,000
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	1,988	$ 2	1,986
Balances at Jun. 30, 2019	$ 846,446	$ 2,219	$ 3,492,736	$ (2,648,509)	$ 0
Balances, in shares at Jun. 30, 2019		221,859,000