Condensed Consolidated Statements of Stockholders' Deficit - USD ($) shares in Thousands, $ in Thousands	Total	2022 Notes	2025 Notes	Series E Preferred Stock	Common Stock	Preferred Stock	Preferred Stock Series E Preferred Stock	Common Stock	Common Stock 2022 Notes	Common Stock 2025 Notes	Common Stock Common Stock	Additional Paid-in Capital	Additional Paid-in Capital 2022 Notes	Additional Paid-in Capital 2025 Notes	Additional Paid-in Capital Series E Preferred Stock	Additional Paid-in Capital Common Stock	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Noncontrolling Interests
Beginning balance at Dec. 31, 2018	$ (36,525)					$ 0		$ 74				$ 546,230					$ (4,877)	$ (577,817)	$ (135)
Beginning Balance (shares) at Dec. 31, 2018						0		73,980
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(27,013)																	(27,070)	57
Foreign currency translation adjustment	(2,912)																(2,912)
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan	1,517							$ 1				1,516
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan (shares)								1,382
Taxes withheld on net settled vesting of restricted stock units	(1,260)											(1,260)
Exercise of warrants	10,639							$ 4				10,635
Exercise of warrants (shares)								4,222
Issuance of shares				$ 10,000	$ 1,279						$ 1				$ 10,000	$ 1,278
Issuance of shares (shares)							10				242
Share-based compensation	5,955											5,955
Series E preferred stock dividends	0											(131)						131
Ending balance at Sep. 30, 2019	(38,320)					$ 0		$ 80				574,485					(7,789)	(605,018)	(78)
Ending Balance (shares) at Sep. 30, 2019						10		79,826
Beginning balance at Jun. 30, 2019	(37,328)					$ 0		$ 79				562,405					(3,670)	(596,081)	(61)
Beginning Balance (shares) at Jun. 30, 2019						0		78,985
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(8,823)																	(8,806)	(17)
Foreign currency translation adjustment	(4,119)																(4,119)
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan	601							$ 0				601
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan (shares)								645
Taxes withheld on net settled vesting of restricted stock units	(942)											(942)
Issuance of shares				10,000	$ 1,038						$ 1				10,000	$ 1,037
Issuance of shares (shares)							10				196
Share-based compensation	1,253											1,253
Series E preferred stock dividends	0											(131)						131
Ending balance at Sep. 30, 2019	(38,320)					$ 0		$ 80				574,485					(7,789)	(605,018)	(78)
Ending Balance (shares) at Sep. 30, 2019						10		79,826
Beginning balance at Dec. 31, 2019	(37,358)					$ 0		$ 82				584,862					(3,879)	(618,303)	(120)
Beginning Balance (shares) at Dec. 31, 2019						10		81,974
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(98,441)																	(98,470)	29
Foreign currency translation adjustment	(10,734)																(10,734)
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan	3,198							$ 2				3,196
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan (shares)								1,471
Taxes withheld on net settled vesting of restricted stock units	(326)											(326)
Exercise of warrants	1,861							$ 0				1,861
Exercise of warrants (shares)								338
Issuance of shares				25,000											25,000
Issuance of shares (shares)							25
Issuance of Series E preferred stock in lieu of interest				$ 2,330											$ 2,330
Issuance of Series E preferred stock in lieu of interest (shares)							2
Repurchase of Series E preferred stock	(2,354)											(2,354)
Repurchase of Series E preferred stock (in shares)						(2)
Issuance of common shares under settlement agreement	972											972
Issuance of common shares under settlement agreement (in shares)								90
Issuance of common shares in connection with conversion of notes		$ 66,088	$ 14,354						$ 14	$ 1			$ 66,074	$ 14,353
Issuance of common shares in connection with conversion of notes (in shares)									13,739	1,177
Share-based compensation	8,188											8,188
Series E preferred stock dividends	0											2,056						(2,056)
Ending balance at Sep. 30, 2020	(27,222)					$ 0		$ 99				706,212					(14,613)	(718,829)	(91)
Ending Balance (shares) at Sep. 30, 2020						35		98,789
Beginning balance at Jun. 30, 2020	(41,928)					$ 0		$ 97				686,410					(15,783)	(712,558)	(94)
Beginning Balance (shares) at Jun. 30, 2020						35		97,018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(5,439)																	(5,442)	3
Foreign currency translation adjustment	1,170																1,170
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan	1,486							$ 1				1,485
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan (shares)								504
Taxes withheld on net settled vesting of restricted stock units	(45)											(45)
Issuance of common shares under settlement agreement	972											972
Issuance of common shares under settlement agreement (in shares)								90
Issuance of common stock in connection with the Notes Exchange	1											1
Issuance of common shares in connection with conversion of notes	14,354							$ 1				14,353
Issuance of common shares in connection with conversion of notes (in shares)								1,177
Share-based compensation	2,207											2,207
Series E preferred stock dividends	0											829						(829)
Ending balance at Sep. 30, 2020	$ (27,222)					$ 0		$ 99				$ 706,212					$ (14,613)	$ (718,829)	$ (91)
Ending Balance (shares) at Sep. 30, 2020						35		98,789