Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (6,417)	$ (66,324)	$ (47,611)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	9,887	10,183	10,061
Write-off of construction in progress			3,440
Loss on disposal of assets		119	230
Debt issuance costs and noncash interest expenses		47	998
Write-off of costs associated with postponed public offering			241
Accretion of debt to fair value		50,011	18,696
Gain on extinguishment of convertible notes			(8,898)
Loss on exchange of convertible notes			5,697
Issuance of Series C preferred stock warrants in connection with senior convertible notes			10,677
Stock compensation expense	5,413	8,781	4,426
Other	(139)	(31)	(25)
Changes in operating assets and liabilities:
Accounts receivable	(2,644)	838	(4,809)
Inventories	(1,635)	1,995	(547)
Prepaid expenses and other assets	(881)	(129)	(287)
Accounts payable	1,517	687	(1,686)
Accrued expenses	(227)	774	2,297
Deferred revenue	333	(303)	(588)
Other liabilities	152		(6,000)
Net cash provided by (used in) operating activities	5,359	6,648	(13,688)
Cash flows from investing activities:
Capital expenditures	(21,956)	(13,241)	(3,329)
Purchase of marketable securities	(2,500)
Maturity and sale of marketable securities	2,500
Net cash used in investing activities	(21,956)	(13,241)	(3,329)
Cash flows from financing activities:
Borrowings under line of credit		4,500	19,929
Repayments under line of credit		(5,500)	(20,267)
Proceeds from issuance of long-term debt			18,500
Repayment of borrowings under long-term debt		(18,849)
Financing costs		(47)	(872)
Proceeds from initial public offering		74,712
Repayment of obligations under capital lease	(80)	(80)	(42)
Payments made for employee restricted stock minimum tax withholdings	(238)
Proceeds from issuance of common stock		2
Net cash (used in) provided by financing activities	(318)	54,738	17,248
Net (decrease) increase in cash	(16,915)	48,145	231
Cash and cash equivalents at beginning of period	49,719	1,574	1,343
Cash and cash equivalents at end of period	32,804	49,719	1,574
Supplemental disclosures of cash flow information:
Interest paid	198	223	228
Income taxes paid	0	0	0
Supplemental disclosures of non-cash activities:
Conversion of convertible and senior convertible notes to common stock		168,510
Accrued dividends on preferred stock			996
Changes in redemption value of redeemable convertible preferred stock			(86,161)
Reclassification of redeemable convertible preferred stock from temporary to permanent equity			(1,085)
Changes in accrued capital expenditures	(5,332)	6,401	(523)
Capitalized interest		34	70
Capital lease	$ 21	$ 5	$ 160