Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 23,749	$ 24,462
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,224	2,777
Stock-based compensation expense	3,940	2,276
Deferred income taxes	943	(571)
Provision for doubtful accounts	(1)	52
Provision for inventory	609	259
Changes in operating assets and liabilities:
Accounts receivable	4,388	(104)
Inventories	(4,668)	(3,229)
Prepaid expenses, other current and long-term assets	(922)	355
Accounts payable	2,030	(5,390)
Accrued expenses and other current liabilities	643	1,091
Income taxes	645	(3,496)
Other long-term liabilities	(749)	(104)
Net cash provided by operating activities	33,831	18,378
Cash flows from investing activities:
Proceeds from maturity of investments	31,250	37,750
Purchase of investments	(36,500)	(32,250)
Purchase of property and equipment	(6,506)	(12,608)
Net cash used in investing activities	(11,756)	(7,108)
Cash flows from financing activities:
Repurchases of common stock	0	(25,000)
Proceeds from exercise of equity awards	310	988
Net cash provided by (used in) financing activities	310	(24,012)
Exchange rate impact on cash	314	82
Increase (decrease) in cash and cash equivalents	22,699	(12,660)
Cash and cash equivalents at beginning of period	104,261	110,707
Cash and cash equivalents at end of period	126,960	98,047
Non-cash investing activities:
Purchases of property and equipment included in accounts payable and accrued expenses	1,208	474
Build-to-suit lease agreement	$ 0	$ 1,825