CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities:
Net income (loss)	$ (1,776)	$ 82
Adjustment to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	2,143	1,282
Amortization and write-off of debt issuance costs	220	96
Revaluation of warrant liability	(559)	177
Stock-based compensation	1,417	885
Changes in operating assets and liabilities:
Accounts receivable	(4,617)	(2,703)
Inventory	(8,649)	(4,254)
Prepaid expenses and other assets	(479)	(218)
Deferred revenue	(27)	(318)
Deferred rent	79	3,804
Accounts payable	377	217
Accrued compensation and benefits	1,118	1,285
Accrued liabilities	1,254	165
Net cash provided by (used in) operating activities	(9,499)	500
Investing activities:
Purchases of investments	(14,116)
Purchases of property and equipment	(2,327)	(6,953)
Net cash used in investing activities	(16,443)	(6,953)
Financing activities:
Proceeds from initial public offering, net of offering costs	68,808
Payments on capital lease financing obligations	(954)	(550)
Payments on term loans	(65,233)	(2,040)
Proceeds from term loans	60,517	12,021
Proceeds from issuance of common stock upon exercise of stock options	556	344
Proceeds from issuance of preferred stock upon exercise of warrants	62
Payments of deferred offering costs		(59)
Net cash provided by (used in) financing activities	63,756	9,716
Net increase (decrease) in cash and cash equivalents	37,814	3,263
Cash and cash equivalents
Beginning of period	10,121	6,939
End of period	$ 47,935	$ 10,202