Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 5,493	$ 6,895
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,014	942
Share-based compensation expense	1,182	817
Deferred income taxes	385	555
Provision for inventory	264	82
Changes in operating assets and liabilities:
Accounts receivable	6,601	7,034
Inventories	(431)	(787)
Prepaid expenses and other current assets	1,115	(267)
Accounts payable	2,020	(3,629)
Accrued expenses and other current liabilities	(1,532)	(1,306)
Income taxes payable	(5)	(2,205)
Long-term deposits and other	(371)
Other long-term liabilities	(275)	(87)
Net cash provided by operating activities	15,460	8,044
Cash flows from investing activities:
Proceeds from maturity of investments	12,500	14,250
Purchase of investments	(11,250)	(9,499)
Purchase of property and equipment	(1,675)	(6,418)
Net cash used in investing activities	(425)	(1,667)
Cash flows from financing activities:
Repurchases of common stock		(25,000)
Proceeds from exercise of equity awards	41	668
Net cash provided by (used in) financing activities	41	(24,332)
Exchange rate impact on cash	31	85
Decrease in cash and cash equivalents	15,107	(17,870)
Cash and cash equivalents at beginning of period	104,261	110,707
Cash and cash equivalents at end of period	119,368	92,837
Non-cash Investing Activities:
Purchases of property and equipment included in accounts payable and accrued expenses	2,081	824
Build-to-suit lease agreement		$ 135