Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net loss	$ (67,462)	$ (22,082)	$ (8,052)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	10,638	10,539	8,259
Provision for doubtful accounts	3,097	1,502	711
Asset impairment and restructuring	3,190	522	249
Gain on business divestiture	(640)	0	0
Amortization of debt issuance costs	145	163	483
Stock-based compensation	10,326	12,696	9,740
Revaluation of contingent consideration liability	0	(1,827)	0
Deferred income tax (benefit) expense	651	642	(35)
Changes in operating assets and liabilities (net of acquisition/divestiture):
Accounts receivable	(18,017)	(2,482)	(13,746)
Inventory	8,840	(19,210)	(5,010)
Prepaid expenses and other assets	(4,759)	(5,281)	(2,512)
Accounts payable, accrued and other liabilities	8,897	(2,620)	25,325
Warranty obligations	867	(3,393)	3,508
Deferred revenues	11,274	9,671	5,302
Net cash (used in) provided by operating activities	(32,953)	(21,160)	24,222
Investing activities:
Purchases of property and equipment	(12,167)	(12,525)	(13,249)
Purchases of intangible assets	(678)	(237)	(750)
Business divestitures (acquisitions)	1,050	0	(2,235)
Change in restricted cash	0	300	(300)
Net cash used in investing activities	(11,795)	(12,462)	(16,534)
Financing activities:
Proceeds from public offering of common stock, net of offering costs	16,142	0	0
Proceeds from term loan, net of issuance costs	23,989	0	0
Proceeds from borrowings under revolving credit facility	10,000	46,000	0
Payments under revolving credit facility	(16,900)	(29,150)	0
Holdback payment related to prior acquisition	0	(300)	0
Repayments of term loans	0	0	(8,708)
Proceeds from issuance of common stock under employee stock plans	1,144	4,014	5,366
Net cash provided by (used in) financing activities	34,375	20,564	(3,342)
Effect of exchange rate changes on cash	(315)	(522)	(504)
Net increase (decrease) in cash and cash equivalents	(10,688)	(13,580)	3,842
Cash and cash equivalents — Beginning of year	28,452	42,032	38,190
Cash and cash equivalents — End of year	17,764	28,452	42,032
Supplemental cash flow disclosure:
Cash paid for interest	2,704	358	1,389
Cash paid for income taxes	1,146	594	472
Noncash financing and investing activities:
Offering and loan costs included in accrued liabilities	518	0	0
Purchases of fixed and intangible assets included in accounts payable	$ 700	$ 1,718	$ 1,840