Condensed Consolidated Statements of Stockholders' Deficit - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance (shares) at Dec. 31, 2021		25	105,381
Beginning balance at Dec. 31, 2021	$ (24,854)	$ 0	$ 105	$ 770,619	$ (787,047)	$ (8,531)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(37,599)				(37,599)
Foreign currency translation adjustment	3,434					3,434
Adjustment relating to extinguishment of 2022 Notes	1,728			1,728
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan (shares)			2,269
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan	$ 151		$ 3	148
Taxes withheld on net settled vesting of restricted stock units (in shares)	(5)
Taxes withheld on net settled vesting of restricted stock units	$ (36)			(36)
Share-based compensation	13,486			13,486
Series E preferred stock dividends	0			1,338	(1,338)
Ending balance (shares) at Jun. 30, 2022		25	107,645
Ending balance at Jun. 30, 2022	(43,690)	$ 0	$ 108	787,283	(825,984)	(5,097)
Beginning balance (shares) at Mar. 31, 2022		25	107,389
Beginning balance at Mar. 31, 2022	(34,190)	$ 0	$ 107	784,267	(812,931)	(5,633)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(12,376)				(12,376)
Foreign currency translation adjustment	536					536
Adjustment relating to extinguishment of 2022 Notes	0			0
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan (shares)			256
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan	75		$ 1	74
Taxes withheld on net settled vesting of restricted stock units	(22)			(22)
Share-based compensation	2,287			2,287
Series E preferred stock dividends	0			677	(677)
Ending balance (shares) at Jun. 30, 2022		25	107,645
Ending balance at Jun. 30, 2022	(43,690)	$ 0	$ 108	787,283	(825,984)	(5,097)
Beginning balance (shares) at Dec. 31, 2022		25	108,468
Beginning balance at Dec. 31, 2022	(70,118)	$ 0	$ 108	793,855	(857,752)	(6,329)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(10,041)				(10,041)
Foreign currency translation adjustment	(525)					(525)
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan (shares)			366
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan	96			96
Taxes withheld on net settled vesting of restricted stock units	(48)			(48)
Issuance of shares (shares)			8,036
Issuance of common shares in connection with a public offering	6,058		$ 9	6,049
Share-based compensation	3,762			3,762
Series E preferred stock dividends	0			1,462	(1,462)
Ending balance (shares) at Jun. 30, 2023		25	116,870
Ending balance at Jun. 30, 2023	(70,815)	$ 0	$ 117	805,177	(869,254)	(6,855)
Beginning balance (shares) at Mar. 31, 2023		25	109,372
Beginning balance at Mar. 31, 2023	(72,724)	$ 0	$ 109	796,981	(863,578)	(6,236)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(4,936)				(4,936)
Foreign currency translation adjustment	(619)					(619)
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan (shares)			320
Exercise of stock options, vesting of restricted stock units and stock issued under employee stock purchase plan	(1)			(1)
Taxes withheld on net settled vesting of restricted stock units	(27)			(27)
Issuance of shares (shares)			7,178
Issuance of common shares in connection with a public offering	5,529		$ 8	5,521
Share-based compensation	1,964			1,964
Series E preferred stock dividends	0			739	(739)
Ending balance (shares) at Jun. 30, 2023		25	116,870
Ending balance at Jun. 30, 2023	$ (70,815)	$ 0	$ 117	$ 805,177	$ (869,254)	$ (6,855)