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	$ 126,959	$ 11,001	$ 14,678
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	5,002	4,258	4,869
Gain on sale of equipment		(248)
Deferred taxes	(82,085)	519	779
Stock-based compensation expense	5,672	5,179	5,575
Provision for doubtful accounts		106
Provision for excess and obsolete inventory	(8,135)	1,051	1,721
Changes in operating assets & liabilities:
Accounts receivable	(23,573)	(14,135)	5,171
Inventories	5,703	(6,572)	(15,938)
Prepaid expenses and other current assets	(3,866)	(1,056)	640
Accounts payable and other current liabilities	25,000	810	6,005
Deferred revenue	7,079	2,467	1,360
Income taxes	14	102	(46)
Other assets and liabilities	(1,486)	(12,270)	(6,547)
Net cash provided by (used in) operating activities	56,284	(8,788)	18,267
Cash flows from investing activities
Proceeds from sale of equipment		270
Expenditures for property, plant and equipment and capitalized software	(7,285)	(2,506)	(1,830)
Net cash used in investing activities	(7,285)	(2,236)	(1,830)
Cash flows from financing activities
Net settlement on restricted stock grants	(1,184)	(11)	(8)
Financing fees and other expenses		(146)	(847)
Principal payments on term loan			(14,530)
Principal payments on sale leaseback obligation			(392)
Proceeds from financing obligations			48,940
Proceeds from Employee Stock Purchase Plan	739	277	441
Proceeds from exercise of stock options	15,515	2,227	3,921
Net cash provided by financing activities	15,070	2,347	37,525
Effect of exchange rate changes on cash and cash equivalents	(844)	507	285
Net increase (decrease) in cash, cash equivalents and restricted cash	63,225	(8,170)	54,247
Cash, cash equivalents and restricted cash at beginning of period	77,655	85,825	31,578
Cash, cash equivalents and restricted cash at end of period	140,880	77,655	85,825
Supplemental disclosure of cash flow information
Cash paid for Income taxes	583	525	669
Cash paid for Interest	$ 5,315	$ 4,815	$ 3,985