CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities
Net income (loss)	$ (1,970)	$ 966
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation expense	1,109	969
Amortization of intangible assets	1,620	1,446
Loss on disposal of fixed assets		14
Provision for doubtful accounts	8	71
Investment discount and premium amortization, net	(169)	(83)
Stock-based compensation	3,529	3,335
Changes in assets and liabilities:
Accounts receivable, net	2,064	3,235
Inventories	(1,741)	(2,003)
Prepaid expenses and other current assets	(3,034)	(916)
Other assets	1,784	194
Accounts payable	(3,887)	(3,923)
Accrued liabilities	(3,395)	(3,083)
Deferred revenue	25	163
Other long-term liabilities	(650)	84
Net cash provided by (used in) operating activities	(4,707)	469
Investing activities
Purchases of available-for-sale investments	(27,171)	(19,501)
Proceeds from sales of available-for-sale investments	1,800	1,000
Proceeds from maturities of available-for-sale investments	26,399	18,200
Purchases of property and equipment	(1,171)	(892)
Business acquisitions, net of cash acquired	(11,695)
Net cash used in investing activities	(11,838)	(1,193)
Financing activities
Proceeds from exercise of options for common stock	310	2,089
Payments for withholding taxes related to net share settlement of equity awards	(1,847)	(3,614)
Repurchase of common stock	(2,522)	(7,448)
Payment of debt issuance costs		(113)
Net cash used in financing activities	(4,059)	(9,086)
Effect of exchange rate changes on cash and cash equivalents	42	48
Net change in cash and cash equivalents	(20,562)	(9,762)
Unrestricted and restricted cash and cash equivalents at beginning of period	40,654	30,034
Unrestricted and restricted cash and cash equivalents at end of period	20,092	20,272
Supplemental disclosure of cash flow information
Cash paid for interest	81	25
Cash paid for taxes	184	167
Supplemental schedule of non-cash investing and financing activities
Settlement of accounts receivable and other assets in business combinations	4,250
Business acquisitions holdback liability	1,310
Purchases of property and equipment financed by accounts payable	61	207
Net unrealized gains (losses) on available-for-sale investments	$ 55	$ (64)