Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net income	$ 28,584	$ 23,438
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,776	2,432
Deferred taxes	6,144	(2,910)
Stock-based compensation expense	3,188	2,580
Provision for excess and obsolete inventory	1,170	1,014
Changes in operating assets & liabilities:
Accounts receivable	530	2,699
Inventories	(9,330)	(7,527)
Prepaid expenses and other current assets	(1,272)	(4,253)
Accounts payable and other current liabilities	(8,032)	10,788
Deferred revenue	(1,358)	3,859
Income taxes	(104)	7
Other assets and liabilities	(6,956)	(730)
Net cash provided by operating activities	15,340	31,397
Cash flows from investing activities
Expenditures for property, plant and equipment and capitalized software	(1,675)	(1,849)
Net cash used in investing activities	(1,675)	(1,849)
Cash flows from financing activities
Net settlement on restricted stock grants	(1,387)	(1,134)
Proceeds from Employee Stock Purchase Plan	437	349
Proceeds from exercise of stock options	822	9,290
Net cash (used in) provided by financing activities	(128)	8,505
Effect of exchange rate changes on cash and cash equivalents	525	(357)
Net increase in cash, cash equivalents and restricted cash	14,062	37,696
Cash, cash equivalents and restricted cash at beginning of period	140,880	77,655
Cash, cash equivalents and restricted cash at end of period	$ 154,942	$ 115,351