Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities
Net income	$ 21,462	$ 41,288
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	30,231	23,891
Stock-based compensation expense	15,539	10,617
Deferred taxes	(139)	6,578
Amortization of marketable securities	374	202
Realized gain on available-sale-securities	(72)	0
Fair value of contingent consideration	(8,513)	0
Other	140	(865)
Changes in operating assets and liabilities:
Accounts receivable	(25,615)	(3,812)
Inventories	950	(316)
Prepaid expenses and other	1,009	(1,008)
Income taxes	(1,226)	(1,325)
Accounts payable	1,978	(1,257)
Accrued liabilities and other	(3,893)	8,382
Net cash provided by operating activities	32,225	82,375
Investing activities
Purchases of property, equipment and other capital assets	(27,956)	(40,489)
Cash used for acquisitions, net of cash acquired	(127,413)	0
Purchases of other assets and investments	0	(3,000)
Purchases of marketable securities	(15,159)	(90,596)
Proceeds from sales of marketable securities	57,089	0
Proceeds from maturities of marketable securities	15,114	56,428
Net cash used in investing activities	(98,325)	(77,657)
Financing activities
Proceeds from exercises of stock options	3,838	5,674
Purchases of shares withheld for tax obligations	(4,209)	(3,367)
Repurchases of common stock	(13,036)	(14,686)
Principal repayments of finance lease obligations	(413)	0
Net cash used in financing activities	(13,820)	(12,379)
Effect of exchange rate changes on cash and cash equivalents	119	690
Net decrease in cash and cash equivalents	(79,801)	(6,971)
Cash and cash equivalents, beginning of period	127,603	125,225
Cash and cash equivalents, end of period	$ 47,802	$ 118,254