Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (18,524)	$ (17,291)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,828	6,890
Stock-based compensation expense	3,797	3,413
Excess tax benefit from stock option exercises	492	0
Amortization of debt issuance costs	291	281
Provision for excess and obsolete inventories	295	196
Contingent consideration expense	0	100
Deferred income taxes	132	126
Net change in operating assets and liabilities	(7,397)	(6,159)
Net cash used in operating activities	(14,086)	(12,444)
Cash flows from investing activities:
Capital expenditures	(1,711)	(1,226)
Net cash used in investing activities	(1,711)	(1,226)
Cash flows from financing activities:
Proceeds from (repayments on) line of credit, net	2,391	(4,998)
Proceeds from the exercise of stock options and employee stock purchase plan, net of tax withholdings on stock compensation awards	181	1,615
Payment of contingent consideration	(79)	(88)
Net cash provided by (used in) financing activities	2,493	(3,471)
Effect of exchange rate changes on cash	9	41
Net decrease in cash and cash equivalents	(13,295)	(17,100)
Cash and cash equivalents at beginning of period	57,237	84,594
Cash and cash equivalents at end of period	43,942	67,494
Supplemental disclosures of cash flow information:
Cash paid for interest	1,586	1,421
Cash paid for income taxes	$ 143	$ 194