Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net income	$ 48,469	$ 57,302
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22,658	19,520
Stock-based compensation expense	9,738	7,986
Deferred taxes	1,599	1,770
Gain on sale of businesses	0	(671)
Amortization of held-to-maturity securities	(5)	336
Other	(133)	160
Changes in operating assets and liabilities:
Accounts receivable	(5,387)	(8,993)
Inventories	551	324
Prepaid expenses and other	(162)	(2,058)
Income taxes	9,165	2,278
Accounts payable	1,479	980
Accrued liabilities and other	(4,193)	6,028
Net cash provided by operating activities	83,779	84,962
Investing activities
Purchases of property, equipment and other capital assets	(46,151)	(61,898)
Cash used for acquisitions, net of cash acquired	0	(90)
Proceeds from sale of business	0	284
Purchases of other assets and investments	(4,000)	(126)
Purchases of marketable securities	(17,443)	(41,384)
Proceeds from maturities of marketable securities	54,352	44,721
Net cash used in investing activities	(13,242)	(58,493)
Financing activities
Payments on debt	0	(5,000)
Proceeds from exercises of stock options	2,486	7,269
Purchases of shares withheld for tax obligations	(2,420)	(2,021)
Repurchases of common stock	(33,521)	0
Net cash (used in) provided by financing activities	(33,455)	248
Effect of exchange rate changes on cash and cash equivalents	(560)	(831)
Net increase in cash and cash equivalents	36,522	25,886
Cash and cash equivalents, beginning of period	85,046	36,707
Cash and cash equivalents, end of period	$ 121,568	$ 62,593