Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (9,078)	$ (1,797)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,676	2,410
Stock-compensation expense	1,244	1,370
Lease incentives	(22)
Other	(1)	(13)
Changes in operating assets and liabilities:
Accounts receivable	442	(2,291)
Inventories	(2,264)	393
Prepaid expenses and other assets	497	966
Accounts payable	2,238	1,508
Accrued expenses	125	(2,203)
Deferred revenue	(254)	(542)
Deferred rent	(22)	(15)
Net cash used in operating activities	(4,419)	(214)
Cash flows from investing activities:
Capital expenditures	(2,146)	(3,128)
Net cash used in investing activities	(2,146)	(3,128)
Cash flows from financing activities:
Repayment of obligations under capital lease	(7)	(23)
Payments made for employee restricted stock tax withholdings	(286)	(82)
Net cash used in financing activities	(293)	(105)
Net decrease in cash	(6,858)	(3,447)
Cash at beginning of period	18,086	32,804
Cash at end of period	11,228	29,357
Supplemental disclosures of cash flow information:
Interest paid	40	52
Supplemental disclosures of non-cash activities:
Changes in accrued capital expenditures	$ (1,134)	484
Advanced billings		$ 292