Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities
Net income	$ 13,984	$ 15,511
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,958	7,439
Stock-based compensation expense	3,033	3,040
Deferred taxes	3,392	379
Amortization of held-to-maturity securities	55	16
Other	(644)	236
Changes in operating assets and liabilities:
Accounts receivable	(5,084)	(2,386)
Inventories	(537)	739
Prepaid expenses and other	(1,240)	(211)
Income taxes	(841)	3,006
Accounts payable	1,739	(805)
Accrued liabilities and other	595	(8,962)
Net cash provided by operating activities	22,410	18,002
Investing activities
Purchases of property, equipment and other capital assets	(13,421)	(12,735)
Purchases of other assets and investments	(3,000)	(4,000)
Purchases of marketable securities	(37,629)	0
Proceeds from maturities of marketable securities	10,700	17,006
Net cash (used in) provided by investing activities	(43,350)	271
Financing activities
Proceeds from exercises of stock options	135	174
Purchases of shares withheld for tax obligations	(1,048)	(594)
Repurchases of common stock	(11,185)	(17,309)
Net cash used in financing activities	(12,098)	(17,729)
Effect of exchange rate changes on cash and cash equivalents	(282)	(240)
Net (decrease) increase in cash and cash equivalents	(33,320)	304
Cash and cash equivalents, beginning of period	125,225	85,046
Cash and cash equivalents, end of period	$ 91,905	$ 85,350