CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Series A Convertible Preferred Stock	Common Stock	Additional paid-in capital	Shareholder note receivable	Treasury stock	Accumulated other comprehensive income (loss)	Accumulated deficit	Accumulated deficit Cumulative Effect, Period of Adoption, Adjustment
Balance at Dec. 31, 2018	$ 17,574			$ 4	$ 523,525	$ (5,000)	$ (97)	$ 1,064	$ (501,922)
Balance, shares at Dec. 31, 2018			4	43,368
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,565				1,565
Distributor equity incentives	42				42
Distributor equity incentives, shares				15
Common stock issued for conversion of Series A preferred stock, shares			(4)	1,858
Recognition of beneficial conversion feature - SafeOp Convertible Notes	242				242
Common stock issued for stock option exercises	14				14
Common stock issued for stock option exercises, shares				8
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability	(183)				(183)
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability, shares				442
Issuance of common stock for acquisition of SafeOp - Milestone 2	2,889				2,889
Issuance of common stock for acquisition of SafeOp - Milestone 2, shares				887
Foreign currency translation adjustments	75							75
Net loss	(12,968)								(12,968)
Balance at Mar. 31, 2019	9,250			$ 4	528,094	(5,000)	(97)	1,139	(514,890)
Balance, shares at Mar. 31, 2019				46,578
Balance at Dec. 31, 2018	17,574			$ 4	523,525	(5,000)	(97)	1,064	(501,922)
Balance, shares at Dec. 31, 2018			4	43,368
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustments	56
Net loss	(39,971)
Balance at Sep. 30, 2019	57,654			$ 6	603,518	(5,000)	(97)	1,120	(541,893)
Balance, shares at Sep. 30, 2019				60,665
Balance at Mar. 31, 2019	9,250			$ 4	528,094	(5,000)	(97)	1,139	(514,890)
Balance, shares at Mar. 31, 2019				46,578
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	2,140				2,140
Distributor equity incentives	138				138
Distributor equity incentives, shares				45
Common stock issued for warrant exercises	723				723
Common stock issued for warrant exercises, shares				255
Common stock issued for employee stock purchase plan and stock option exercises	664				664
Common stock issued for employee stock purchase plan and stock option exercises, shares				278
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability, shares				217
Issuance of common stock warrants	13,664				13,664
Foreign currency translation adjustments	18							18
Net loss	(12,436)								(12,436)
Balance at Jun. 30, 2019	14,161			$ 4	545,423	(5,000)	(97)	1,157	(527,326)
Balance, shares at Jun. 30, 2019				47,373
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	3,411				3,411
Distributor equity incentives	40				40
Distributor equity incentives, shares				15
Common stock issued for conversion of Series A preferred stock, shares				97
Common stock issued for warrant exercises	600				600
Common stock issued for warrant exercises, shares				333
Common stock issued for employee stock purchase plan and stock option exercises	102				102
Common stock issued for employee stock purchase plan and stock option exercises, shares				26
Common stock issued for vesting of performance and restricted stock awards, net of shares repurchased for tax liability	(30)				(30)
Common stock issued for vesting of performance and restricted stock awards, net of shares repurchased for tax liability, shares				286
Issuance of common stock for public offering, net of offering costs	53,974			$ 2	53,972
Issuance of common stock for public offering, net of offering costs, shares				12,535
Foreign currency translation adjustments	(37)							(37)
Net loss	(14,567)								(14,567)
Balance at Sep. 30, 2019	57,654			$ 6	603,518	(5,000)	(97)	1,120	(541,893)
Balance, shares at Sep. 30, 2019				60,665
Balance at Dec. 31, 2019	$ 43,631	$ (81)		$ 6	606,558	(5,000)	(97)	1,088	(558,924)	$ (81)
Balance, shares at Dec. 31, 2019				61,400
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201908Member
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	$ 3,630				3,630
Distributor equity incentives	70				70
Common stock issued for warrant exercises	1,158				1,158
Common stock issued for warrant exercises, shares				1,390
Common stock issued for employee stock purchase plan and stock option exercises	83				83
Common stock issued for employee stock purchase plan and stock option exercises, shares				76
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability	(408)				(408)
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability, shares				394
Foreign currency translation adjustments	69							69
Net loss	(20,722)								(20,722)
Balance at Mar. 31, 2020	27,430			$ 6	611,091	(5,000)	(97)	1,157	(579,727)
Balance, shares at Mar. 31, 2020				63,260
Balance at Dec. 31, 2019	43,631	$ (81)		$ 6	606,558	(5,000)	(97)	1,088	(558,924)	$ (81)
Balance, shares at Dec. 31, 2019				61,400
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustments	93
Net loss	(52,196)
Balance at Sep. 30, 2020	8,051			$ 6	623,162	(5,000)	(97)	1,181	(611,201)
Balance, shares at Sep. 30, 2020				64,562
Balance at Mar. 31, 2020	27,430			$ 6	611,091	(5,000)	(97)	1,157	(579,727)
Balance, shares at Mar. 31, 2020				63,260
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	3,608				3,608
Distributor equity incentives	51				51
Common stock issued for employee stock purchase plan and stock option exercises	722				722
Common stock issued for employee stock purchase plan and stock option exercises, shares				202
Common stock issued for vesting of performance and restricted stock awards, net of shares repurchased for tax liability	(164)				(164)
Common stock issued for vesting of performance and restricted stock awards, net of shares repurchased for tax liability, shares				387
Issuance of common stock warrants	2,974				2,974
Foreign currency translation adjustments	6							6
Net loss	(15,805)								(15,805)
Balance at Jun. 30, 2020	18,822			$ 6	618,282	(5,000)	(97)	1,163	(595,532)
Balance, shares at Jun. 30, 2020				63,849
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	4,761				4,761
Distributor equity incentives	293				293
Distributor equity incentives, shares				34
Common stock issued for conversion of Series A preferred stock, shares				39
Common stock issued for warrant exercises, shares				68
Common stock issued for employee stock purchase plan and stock option exercises	70				70
Common stock issued for employee stock purchase plan and stock option exercises, shares				24
Common stock issued for vesting of performance and restricted stock awards, net of shares repurchased for tax liability	(244)				(244)
Common stock issued for vesting of performance and restricted stock awards, net of shares repurchased for tax liability, shares				548
Foreign currency translation adjustments	18							18
Net loss	(15,669)								(15,669)
Balance at Sep. 30, 2020	$ 8,051			$ 6	$ 623,162	$ (5,000)	$ (97)	$ 1,181	$ (611,201)
Balance, shares at Sep. 30, 2020				64,562