Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (67,865)	$ (86,350)	$ (115,204)
Adjustments to reconcile loss to net cash used in operating activities:
Depreciation and amortization	62	138	166
Loss on sale of fixed assets		48
Allowance for doubtful accounts		12
Stock-based compensation	13,960	13,613	13,889
Amortization of debt discount and debt issuance costs	2,332	7,783	8,258
Amortization of intangible asset	646	645	646
Gain (loss) on change in fair value of derivative liabilities		(8,170)	1,106
Gain on extinguishment of debt			(1,314)
Deferred income taxes	11,082	8,798	(4,252)
Changes in assets and liabilities:
Accounts receivable, net	(25,333)	(6,171)	(5,984)
Inventory	(9,753)	(1,522)	(5,252)
Prepaid and other current assets	6,028	(3,831)	(519)
Other long-term assets	567	(567)	431
Accrued interest payable	(6,491)	(6,205)	(652)
Deferred revenue	1,221	884	14,231
Accounts payable and other current liabilities	40,267	8,705	10,489
Other long-term liabilities	440	375	(51)
Net cash used in operating activities	(32,837)	(71,815)	(84,021)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of equipment	(12)	(21)	(28)
Net cash used in investing activities	(12)	(21)	(28)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of exchangeable debt	30,000
Proceeds from issuance of preferred stock, net of transaction costs			57,666
Proceeds from issuance of common stock, net of transaction costs		64,613
Proceeds from issuance of convertible debt, net of transaction costs			27,514
Proceeds from exercise of warrants, net of transaction costs			2,713
Proceeds from exercise of stock options, net of transaction costs	638	287	31
Payment of debt issuance costs	(1,207)		(109)
Repurchase of exchangeable senior notes, including transaction costs	(15,107)		(16,145)
Payment on long-term debt from royalty-bearing instrument	(3,322)
Transaction costs related to exchange of exchangeable senior notes		(680)
Taxes paid related to stock-based awards	(2,767)	(1,094)	(194)
Payment under capital leases			(5)
Net cash provided by financing activities	8,235	63,126	71,471
NET DECREASE IN CASH AND CASH EQUIVALENTS	(24,614)	(8,710)	(12,578)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	98,251	106,961	119,539
CASH AND CASH EQUIVALENTS, END OF PERIOD	73,637	98,251	106,961
Cash paid during the year for:
Interest	17,241	17,083	12,559
Income taxes	$ 1,753	1,457	711
Supplemental disclosure of non-cash transactions:
Exchange of exchangeable senior notes into common stock		$ 128,115
Transfer of preferred stock purchase option derivative liability to equity			868
Accretion of preferred stock beneficial conversion features			32,987
Conversion of Series A Convertible Preferred Stock into common stock			4,804
Reacquisition of conversion option in convertible notes			1,300
Warrant
Adjustments to reconcile loss to net cash used in operating activities:
Stock-based compensation			$ (9)