Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities
Net income	$ 35,386	$ 24,523
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,336	4,829
Deferred income taxes	5,107	3,035
Stock-based compensation expense	5,784	4,806
Provision for excess and obsolete inventory	1,888	1,708
Changes in operating assets and liabilities:
Accounts receivable	7,091	18,752
Inventories	(32,418)	(9,123)
Prepaid expenses and other current assets	(3,309)	(4,206)
Accounts payable and other current liabilities	7,282	11,808
Deferred revenue	12,460	1,167
Income taxes	(27)	5
Other assets and liabilities	1,341	(729)
Net cash provided by operating activities	45,921	56,575
Cash flows from investing activities
Expenditures for property, plant and equipment and capitalized software	(2,392)	(2,975)
Net cash used in investing activities	(2,392)	(2,975)
Cash flows from financing activities
Net settlement on restricted stock grants	(6,495)	(3,860)
Repurchase of common stock	(24,993)	(7,501)
Proceeds from Employee Stock Purchase Plan	508	509
Principal payments on finance lease obligation	(362)	(108)
Proceeds from exercise of stock options	3,075	7,282
Net cash used in financing activities	(28,267)	(3,678)
Effect of exchange rate changes on cash and cash equivalents	992	560
Net increase in cash, cash equivalents and restricted cash	16,254	50,482
Cash, cash equivalents and restricted cash at beginning of period	204,232	146,534
Cash, cash equivalents and restricted cash at end of period	$ 220,486	$ 197,016