Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ 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
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
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
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(48,873)
Other comprehensive income (loss)	(173)
Balances at Sep. 30, 2018	767,783	$ 1,870	3,359,183	(2,593,012)	(258)
Balances, in shares at Sep. 30, 2018		187,027
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new accounting standard				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
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
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new accounting standard	0
NET INCOME (LOSS)	(53,044)			(53,044)
Other comprehensive income (loss)	192				192
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		(47)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	1,864	$ (1)	1,865
Balances at Sep. 30, 2018	767,783	$ 1,870	3,359,183	(2,593,012)	(258)
Balances, in shares at Sep. 30, 2018		187,027
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
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
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
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(70,242)
Other comprehensive income (loss)	1,191
Balances at Sep. 30, 2019	930,807	$ 2,405	3,590,056	(2,662,786)	1,132
Balances, in shares at Sep. 30, 2019		240,509
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(36,764)			(36,764)
Stock Issued During Period, Shares, New Issues		16,631
Stock Issued During Period, Value, New Issues	48,887	$ 166	48,721
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		117
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(14,277)			(14,277)
Other comprehensive income (loss)	1,132				1,132
Stock Issued During Period, Shares, Extinguishment of Debt		4,452
Stock Issued During Period, Value, Extinguishment of Debt	21,290	$ 44	21,246	0	0
Stock Issued During Period, Shares, New Issues		14,220
Stock Issued During Period, Value, New Issues	73,781	$ 142	73,639
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		(22)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	2,435	$ 0	2,435
Balances at Sep. 30, 2019	$ 930,807	$ 2,405	$ 3,590,056	$ (2,662,786)	$ 1,132
Balances, in shares at Sep. 30, 2019		240,509