CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)
In Thousands, unless otherwise specified
9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Operating activities    
Net income $ 4,235 $ 1,233
Adjustments to reconcile net income to net cash provided by operating activities:    
Depreciation expense 1,880 1,609
Amortization of intangible assets 330 218
Provision for doubtful accounts 271 112
Gain on inventory purchase commitment   (180)
Stock-based compensation 3,994 2,648
Excess tax benefit from exercise of options for common stock (18)  
Warrant liability expense   709
Changes in assets and liabilities:    
Accounts receivable (4,338) (2,978)
Inventories (175) (2,947)
Restricted cash (334)  
Prepaid expenses and other current assets (402) (98)
Other assets (24) (243)
Accounts payable 956 2,150
Accrued liabilities (2,072) (838)
Deferred revenue 99 95
Other long-term liabilities (26) (1,138)
Net cash provided by operating activities 4,376 352
Investing activities    
Purchases of available-for-sale investments (86,765)  
Proceeds from sales of available-for-sale investments 2,850  
Proceeds from maturities of available-for-sale investments 11,915  
Purchases of property and equipment (2,148) (2,575)
Business acquisitions, net of cash acquired (1,116) (88)
Net cash used in investing activities (75,264) (2,663)
Financing activities    
Proceeds from issuance of common stock, net of issuance costs   65,556
Proceeds from exercise of options for common stock 4,630 367
Excess tax benefit from exercise of options for common stock 18  
Proceeds from notes payable   1,145
Repayment of notes payable (847) (986)
Net cash provided by financing activities 3,801 66,082
Effect of exchange rate changes on cash and cash equivalents (9) 19
Net decrease in cash and cash equivalents (67,096) 63,790
Cash and cash equivalents at beginning of period 84,546 18,695
Cash and cash equivalents at end of period 17,450 82,485
Supplemental disclosure of cash flow information    
Cash paid for interest 150 419
Cash paid for taxes 227 131
Supplemental schedule of non-cash investing and financing activities    
Options for common stock granted in connection with a business acquisition   174
Elimination of liability upon net exercise of warrants to purchase preferred stock   1,310
Conversion of redeemable convertible preferred stock to common stock   $ 116,313