CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Income	Treasury Stock	Accumulated Deficit	Total
Balance at Dec. 31, 2017	$ 2,291	$ 1,250,899	$ 2,194	$ (3,102)	$ (1,182,053)	$ 70,229
Balance (in shares) at Dec. 31, 2017	229,073,517			587,151
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company					(85,608)	(85,608)
Other comprehensive (loss) gain			(610)			(610)
Stock-based compensation	$ 8	8,763				8,771
Stock-based compensation (in shares)	741,216
Stock dividend		52			(52)
Stock dividend (in shares)	29,762
Public offerings, common stock, net	$ 38	6,978				7,016
Public offerings, common stock, net (in shares)	3,804,654
Stock option exercises	$ 5	168		$ (35)		138
Stock option exercises (in shares)	511,412			17,606
Equity component of 3.75% Convertible Senior Notes issued, net of issuance costs and income tax expense		28,586				28,586
Purchase of capped calls		(16,000)				(16,000)
Purchase of common stock forward				$ (27,500)		(27,500)
Purchase of common stock forward (in shares)				14,397,906
Exercise of warrants (in shares)	100
Provision for common stock warrants		10,190				10,190
Balance (Cumulative effect from adoption of ASC 842) at Dec. 31, 2018					1,200	1,200
Balance at Dec. 31, 2018	$ 2,342	1,289,636	1,584	$ (30,637)	(1,266,513)	(3,588)
Balance (in shares) at Dec. 31, 2018	234,160,661			15,002,663
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						(30,547)
Balance at Mar. 31, 2019	$ 2,445	1,316,815	1,374	$ (30,637)	(1,297,072)	$ (7,075)
Balance (in shares) at Mar. 31, 2019	244,537,235			15,002,663		244,537,235
Balance (Cumulative effect from adoption of ASC 842) at Dec. 31, 2018					1,200	$ 1,200
Balance at Dec. 31, 2018	$ 2,342	1,289,636	1,584	$ (30,637)	(1,266,513)	(3,588)
Balance (in shares) at Dec. 31, 2018	234,160,661			15,002,663
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						(47,885)
Balance at Jun. 30, 2019	$ 2,470	1,325,381	1,460	$ (30,681)	(1,314,425)	$ (15,795)
Balance (in shares) at Jun. 30, 2019	246,975,173			15,020,437		246,975,173
Balance (Cumulative effect from adoption of ASC 842) at Dec. 31, 2018					1,200	$ 1,200
Balance at Dec. 31, 2018	$ 2,342	1,289,636	1,584	$ (30,637)	(1,266,513)	(3,588)
Balance (in shares) at Dec. 31, 2018	234,160,661			15,002,663
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						(65,707)
Balance at Sep. 30, 2019	$ 2,540	1,340,781	929	$ (31,216)	(1,332,259)	$ (19,225)
Balance (in shares) at Sep. 30, 2019	253,982,578			15,259,045		253,982,578
Balance (Cumulative effect from adoption of ASC 842) at Dec. 31, 2018					1,200	$ 1,200
Balance at Dec. 31, 2018	$ 2,342	1,289,636	1,584	$ (30,637)	(1,266,513)	(3,588)
Balance (in shares) at Dec. 31, 2018	234,160,661			15,002,663
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company					(83,743)	(83,743)
Other comprehensive (loss) gain			(296)			(296)
Stock-based compensation	$ 19	10,871				10,890
Stock-based compensation (in shares)	1,876,503
Stock dividend		52			(52)
Stock dividend (in shares)	19,286
Public offerings, common stock, net	$ 622	157,722				158,344
Public offerings, common stock, net (in shares)	62,333,585
Stock option exercises	$ 12	1,784		$ (579)		1,217
Stock option exercises (in shares)	1,151,307			256,382
Exercise of warrants	$ 53	14,099				14,152
Exercise of warrants (in shares)	5,250,750
Provision for common stock warrants		6,513				6,513
Accretion of discount, preferred stock		(1,978)				(1,978)
Conversion of preferred stock	$ 138	28,254				28,392
Conversion of preferred stock (in shares)	13,845,468
Balance at Dec. 31, 2019	$ 3,186	1,506,953	1,288	$ (31,216)	(1,350,307)	$ 129,904
Balance (in shares) at Dec. 31, 2019	318,637,560			15,259,045		318,637,560
Balance at Mar. 31, 2019	$ 2,445	1,316,815	1,374	$ (30,637)	(1,297,072)	$ (7,075)
Balance (in shares) at Mar. 31, 2019	244,537,235			15,002,663		244,537,235
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						$ (17,338)
Balance at Jun. 30, 2019	$ 2,470	1,325,381	1,460	$ (30,681)	(1,314,425)	$ (15,795)
Balance (in shares) at Jun. 30, 2019	246,975,173			15,020,437		246,975,173
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						$ (17,822)
Balance at Sep. 30, 2019	$ 2,540	1,340,781	929	$ (31,216)	(1,332,259)	$ (19,225)
Balance (in shares) at Sep. 30, 2019	253,982,578			15,259,045		253,982,578
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						$ (18,036)
Balance at Dec. 31, 2019	$ 3,186	1,506,953	1,288	$ (31,216)	(1,350,307)	$ 129,904
Balance (in shares) at Dec. 31, 2019	318,637,560			15,259,045		318,637,560
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						$ (37,432)
Balance at Mar. 31, 2020	$ 3,222	1,519,094	1,052	$ (31,224)	(1,387,752)	$ 104,392
Balance (in shares) at Mar. 31, 2020	322,220,469			15,261,007		322,220,469
Balance at Dec. 31, 2019	$ 3,186	1,506,953	1,288	$ (31,216)	(1,350,307)	$ 129,904
Balance (in shares) at Dec. 31, 2019	318,637,560			15,259,045		318,637,560
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						$ (46,833)
Balance at Jun. 30, 2020	$ 3,482	1,658,438	1,159	$ (31,359)	(1,397,160)	$ 234,560
Balance (in shares) at Jun. 30, 2020	348,201,792			15,292,591		348,201,792
Balance at Dec. 31, 2019	$ 3,186	1,506,953	1,288	$ (31,216)	(1,350,307)	$ 129,904
Balance (in shares) at Dec. 31, 2019	318,637,560			15,259,045		318,637,560
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						$ (112,050)
Balance at Sep. 30, 2020	$ 4,061	2,083,169	1,846	$ (40,434)	(1,462,377)	$ 586,265
Balance (in shares) at Sep. 30, 2020	406,123,816			15,926,068		406,123,816
Balance at Dec. 31, 2019	$ 3,186	1,506,953	1,288	$ (31,216)	(1,350,307)	$ 129,904
Balance (in shares) at Dec. 31, 2019	318,637,560			15,259,045		318,637,560
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company					(596,155)	$ (596,155)
Other comprehensive (loss) gain			1,163			1,163
Stock-based compensation	$ 4	17,131				17,135
Stock-based compensation (in shares)	439,649
Stock dividend		26			(26)
Stock dividend (in shares)	5,156
Public offerings, common stock, net	$ 790	1,270,872				$ 1,271,662
Public offerings, common stock, net (in shares)	78,976,250					79,000,000.0
Stock option exercises	$ 181	41,060		$ (9,218)		$ 32,023
Stock option exercises (in shares)	18,056,200			667,023
Equity component of 3.75% Convertible Senior Notes issued, net of issuance costs and income tax expense		100,761				100,761
Purchase of capped calls		(16,253)				(16,253)
Termination of capped calls		24,158				24,158
Exercise of warrants	$ 52	(52)
Exercise of warrants (in shares)	5,180,457
Provision for common stock warrants		439,915				439,915
Accretion of discount, preferred stock		(29)				(29)
Conversion of preferred stock	$ 30	1,149				1,179
Conversion of preferred stock (in shares)	2,998,526
Conversion of 5.5% and 7.5% Convertible Senior Notes	$ 306	62,247				62,553
Conversion of 5.5% and 7.5% Convertible Senior Notes (in shares)	30,615,615
Repurchase of 5.5% Convertible Senior Notes, net of income tax benefit	$ 94	(50,864)				(50,770)
Repurchase of 5.5% Convertible Senior Notes, net of income tax benefit (in shares)	9,409,591
Shares issued for acquisitions	$ 97	49,576				49,673
Shares issued for acquisitions (in shares)	9,658,465
Balance at Dec. 31, 2020	$ 4,740	3,446,650	2,451	$ (40,434)	(1,946,488)	$ 1,466,919
Balance (in shares) at Dec. 31, 2020	473,977,469			15,926,068		473,977,469
Balance at Mar. 31, 2020	$ 3,222	1,519,094	1,052	$ (31,224)	(1,387,752)	$ 104,392
Balance (in shares) at Mar. 31, 2020	322,220,469			15,261,007		322,220,469
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						$ (9,401)
Balance at Jun. 30, 2020	$ 3,482	1,658,438	1,159	$ (31,359)	(1,397,160)	$ 234,560
Balance (in shares) at Jun. 30, 2020	348,201,792			15,292,591		348,201,792
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company						$ (65,217)
Balance at Sep. 30, 2020	$ 4,061	2,083,169	1,846	$ (40,434)	(1,462,377)	$ 586,265
Balance (in shares) at Sep. 30, 2020	406,123,816			15,926,068		406,123,816
Increase (Decrease) in Stockholders' Equity
Public offerings, common stock, net (in shares)						4,400,000
Balance at Dec. 31, 2020	$ 4,740	$ 3,446,650	$ 2,451	$ (40,434)	$ (1,946,488)	$ 1,466,919
Balance (in shares) at Dec. 31, 2020	473,977,469			15,926,068		473,977,469