Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net income	$ 62,901	$ 35,308
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,993	7,346
Deferred income taxes	11,558	5,399
Stock-based compensation expense	8,970	7,727
Provision for excess and obsolete inventory	2,773	2,736
Changes in operating assets and liabilities:
Accounts receivable	8,133	39,109
Inventories	(39,595)	(18,611)
Prepaid expenses and other current assets	(4,879)	(2,704)
Accounts payable and other current liabilities	17,933	10,540
Deferred revenue	35,189	(12,292)
Income taxes	(24)	29
Other assets and liabilities	1,129	1,080
Net cash provided by operating activities	112,081	75,667
Cash flows from investing activities
Expenditures for property, plant and equipment and capitalized software	(5,701)	(5,567)
Net cash used in investing activities	(5,701)	(5,567)
Cash flows from financing activities
Net settlement on restricted stock grants	(6,543)	(3,888)
Repurchase of common stock	(37,493)	(7,501)
Proceeds from Employee Stock Purchase Plan	509	509
Principal payments on finance lease obligation	(562)	(252)
Proceeds from exercise of stock options	3,419	7,740
Net cash used in financing activities	(40,670)	(3,392)
Effect of exchange rate changes on cash and cash equivalents	1,899	(525)
Net increase in cash, cash equivalents and restricted cash	67,609	66,183
Cash, cash equivalents and restricted cash at beginning of period	204,232	146,534
Cash, cash equivalents and restricted cash at end of period	$ 271,841	$ 212,717