Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ (52,604)	$ (10,251)	$ (14,678)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	17,219	17,256	18,478
Inventory valuation allowance and adverse purch commitment charges	17,963	4,212	3,278
Deferred income taxes and uncertain tax positions	1,645	124	106
Stock-based compensation expense	2,192	3,797	3,952
Gain (Loss) on Disposition of Property Plant Equipment	(313)
Restructuring Costs and Asset Impairment Charges	1,743	40	225
Other	327	(815)	(217)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	5,463	22,609	(17,121)
Other receivables	808	7,110	(5,040)
Inventories and deferred cost of sales	620	4,890	(13,801)
Accounts payable	(2,237)	(22,805)	9,853
Accrued wages and bonuses	(2,664)	(789)	2,043
Accrued restructuring	(1,338)	772	(89)
Deferred revenue	(2,786)	(14,967)	16,682
Other	3,191	(1,334)	1,611
Net cash provided by (used in) operating activities	(11,888)	9,809	5,057
Cash flows from investing activities:
Capital expenditures	(4,898)	(4,931)	(2,224)
Net cash used in investing activities	(4,898)	(4,931)	(2,224)
Cash flows from financing activities:
Payments on line of credit	93,000	98,000	13,500
Payments on line of credit	(102,000)	(88,000)	(8,500)
Repayment of convertible subordinated notes	0	0	(18,000)
Net resettlement of restricted shares	516	1,040	331
Net resettlement of restricted shares	(204)	(3,287)	(142)
Other financing activities	68	(279)	0
Net cash provided by (used in) financing activities	(8,620)	7,474	(12,811)
Effect of exchange rate changes on cash	443	(29)	(500)
Net increase (decrease) in cash and cash equivalents	(24,963)	12,323	(10,478)
Cash and cash equivalents, beginning of period	33,087		20,764
Cash and cash equivalents, end of period	8,124	33,087
Supplemental disclosure of cash flow information:
Interest	906	483	835
Income taxes	$ 1,262	$ 1,349	$ 1,289