Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (30,889)	$ (24,180)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	913	737
Stock-based compensation	531	262
Change in fair value of convertible preferred stock warrant liability	(45)	(74)
Inventory lower of cost and market adjustment	995	598
Write-off of deferred offering cost	2,920
Amortization of debt discount and interest accrual	573	138
Changes in operating assets and liabilities:
Accounts receivable	903	(2,004)
Inventory	(2,406)	(3,037)
Deposits on purchased inventory	(2,223)	(1,387)
Deferred costs	409
Prepaid expenses and other current assets	(664)	(214)
Accounts payable	(6,048)	8
Notes payable	(240)
Accrued expenses and other long-term liabilities	392	(576)
Customer deposits and deferred revenue	3,574	2,522
Net cash used in operating activities	(31,305)	(27,207)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(2,906)	(1,397)
Change in restricted cash balance	500	(100)
Net cash used in investing activities	(2,406)	(1,497)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of convertible notes, net		3,904
Repurchase of Series A convertible preferred stock		(37)
Proceeds from issuance of convertible preferred stock, net	15,729
Proceeds from draw down of long-term debt, net	27,381
Payments of long-term debt	(15,000)
Proceeds from common stock private placement, gross	29,447
Payment of offering costs related to common stock private placement	(2,302)
Payments of costs related to the initial public offering	(628)
Proceeds from the exercise of stock options	19	21
Net cash provided by financing activities	54,646	3,888
NET INCREASE (DECREASE) IN CASH	20,935	(24,816)
CASH — BEGINNING OF PERIOD	11,129	26,529
CASH — END OF PERIOD	32,064	1,713
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest	1,711	1,111
SUPPLEMENTAL NON-CASH INVESTING AND FINANCING ACTIVITIES:
Purchase of fixed assets in accounts payable and accrued expenses	(309)	$ 150
Fair value of common stock warrants issued to placement agents as service payment	316
Offering cost in accounts payable and accrued expenses	$ 605