Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities
Net income	$ 6,618	$ 28,584
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	3,600	2,776
Deferred income taxes	1,341	6,144
Stock-based compensation expense	3,989	3,188
Provision for excess and obsolete inventory	1,329	1,170
Changes in operating assets & liabilities:
Accounts receivable	16,346	530
Inventories	(11,161)	(9,330)
Prepaid expenses and other current assets	(433)	(1,272)
Accounts payable and other current liabilities	(21,559)	(8,032)
Deferred revenue	(8,498)	(1,358)
Income taxes	(129)	(104)
Other assets and liabilities	(11,769)	(6,956)
Net cash (used in) provided by operating activities	(20,326)	15,340
Cash flows from investing activities
Expenditures for property, plant and equipment and capitalized software	(8,757)	(1,675)
Net cash used in investing activities	(8,757)	(1,675)
Cash flows from financing activities
Net settlement on restricted stock grants	(1,591)	(1,387)
Repurchase of common stock	(14,035)
Proceeds from Employee Stock Purchase Plan	407	437
Proceeds from exercise of stock options	2,396	822
Net cash used in financing activities	(12,823)	(128)
Effect of exchange rate changes on cash and cash equivalents	168	525
Net (decrease) increase in cash, cash equivalents and restricted cash	(41,738)	14,062
Cash, cash equivalents and restricted cash at beginning of period	184,902	140,880
Cash, cash equivalents and restricted cash at end of period	$ 143,164	$ 154,942