| Balance Sheet Data | Marketable Securities Marketable securities included available-for-sale securities as follows (in thousands):
| | | As of September 30, 2011 | | | | | Amortized Cost | | | Unrealized Gain | | | Unrealized Loss | | | Estimated Fair Value | | | | | | | | | | | | | | | | Corporate debt securities | | $ | 77,254 | | | $ | 44 | | | $ | (160 | ) | | $ | 77,138 | | U.S. Agency debt securities | | | 19,122 | | | | 8 | | | | (1 | ) | | | 19,129 | | Commercial paper | | | 6,745 | | | | 3 | | | | - | | | | 6,748 | | Total marketable securities | | $ | 103,121 | | | $ | 55 | | | $ | (161 | ) | | $ | 103,015 | |
| | | As of December 31, 2010 | | | | | Amortized Cost | | | Unrealized Gain | | | Unrealized Loss | | | Estimated Fair Value | | | | | | | | | | | | | | | | Corporate debt securities | | $ | 69,627 | | | $ | 131 | | | $ | (30 | ) | | $ | 69,728 | | U.S. Agency debt securities | | | 43,795 | | | | 8 | | | | (12 | ) | | | 43,791 | | Commercial paper | | | 8,491 | | | | 2 | | | | - | | | | 8,493 | | Total marketable securities | | $ | 121,913 | | | $ | 141 | | | $ | (42 | ) | | $ | 122,012 | |
The contractual maturity date of the available-for-sale securities was as follows (in thousands): | | | As of September 30, | | | As of December 31, | | | | | 2011 | | | 2010 | | | | | | | | | | Due within one year | | $ | 60,685 | | | $ | 97,179 | | Due within one to two years | | | 42,330 | | | | 24,833 | | Total marketable securities | | $ | 103,015 | | | $ | 122,012 | |
Inventories, Net Inventories, net were comprised as follows (in thousands): | | | As of September 30, | | | As of December 31, | | | | | 2011 | | | 2010 | | | | | | | | | | Finished products | | $ | 6,020 | | | $ | 9,110 | | Raw materials | | | 2,227 | | | | 2,007 | | Total inventories, net | | $ | 8,247 | | | $ | 11,117 | |
Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets were comprised as follows (in thousands): | | | As of September 30, | | | As of December 31, | | | | | 2011 | | | 2010 | | | | | | | | | | Interest receivable | | $ | 1,101 | | | $ | 1,156 | | Prepaid maintenance | | | 591 | | | | 813 | | Taxes receivable | | | 590 | | | | 543 | | Other | | | 1,404 | | | | 1,678 | | Total prepaid expenses and other current assets | | $ | 3,686 | | | $ | 4,190 | |
Property and Equipment, Net Property and equipment, net is stated at cost, less accumulated depreciation. Depreciation is calculated using the straight-line method and recorded over the assets' estimated useful lives of 18 months to seven years. Property and equipment, net was comprised as follows (in thousands): | | | As of September 30, | | | As of December 31, | | | | | 2011 | | | 2010 | | | | | | | | | | Engineering and other equipment | | $ | 24,229 | | | $ | 22,238 | | Computers, software and related equipment | | | 17,580 | | | | 17,215 | | Leasehold improvements | | | 3,427 | | | | 5,115 | | Office furniture and fixtures | | | 953 | | | | 1,110 | | | | | | 46,189 | | | | 45,678 | | Less: accumulated depreciation | | | (39,735 | ) | | | (37,590 | ) | Total property and equipment, net | | $ | 6,454 | | | $ | 8,088 | |
Goodwill Goodwill is carried at cost and is not amortized. The carrying value of goodwill was approximately $1.7 million as of September 30, 2011 and December 31, 2010. Other Non-current Assets Other non-current assets were comprised as follows (in thousands): | | | As of September 30, | | | As of December 31, | | | | | 2011 | | | 2010 | | | | | | | | | | Israeli severance pay | | $ | 3,568 | | | $ | 3,933 | | Security deposits | | | 1,708 | | | | 2,083 | | Deferred tax assets | | | 502 | | | | 530 | | Other | | | 185 | | | | 624 | | Total other non-current assets | | $ | 5,963 | | | $ | 7,170 | |
Deferred Revenues, Net Deferred revenues, net were as follows (in thousands):
| | | As of September 30, | | | As of December 31, | | | | | 2011 | | | 2010 | | | | | | | | | | Deferred service revenues, net | | $ | 19,510 | | | $ | 22,091 | | Deferred product revenues, net | | | 3,218 | | | | 4,379 | | Total deferred revenues, net | | | 22,728 | | | | 26,470 | | Less current portion of deferred revenues, net | | | (15,941 | ) | | | (18,143 | ) | Deferred revenues, net, less current portion | | $ | 6,787 | | | $ | 8,327 | |
Other Liabilities Other liabilities were comprised as follows (in thousands): | | | As of September 30, | | | As of December 31, | | | | | 2011 | | | 2010 | | | | | | | | | | Foreign, franchise and other income tax liabilities | | $ | 1,550 | | | $ | 1,230 | | Accrued professional fees | | | 1,096 | | | | 480 | | Accrued warranty | | | 746 | | | | 1,147 | | Deferred rent and restructuring liabilities | | | 624 | | | | 1,015 | | Sales and use tax payable | | | 247 | | | | 245 | | Other | | | 961 | | | | 1,841 | | Total other liabilities | | | 5,224 | | | | 5,958 | | Less current portion of other liabilities | | | (3,822 | ) | | | (4,266 | ) | Other liabilities, less current portion | | $ | 1,402 | | | $ | 1,692 | |
Accrued Warranty Activity related to product warranty was as follows (in thousands): | | | Nine Months Ended September 30, | | | | | 2011 | | | 2010 | | | | | | | | | | Balance as of beginning of period | | $ | 1,147 | | | $ | 2,068 | | Warranty charged to cost of sales | | | 464 | | | | 355 | | Utilization of warranty | | | (488 | ) | | | (691 | ) | Other adjustments | | | (377 | ) | | | (286 | ) | Balance as of end of period | | | 746 | | | | 1,446 | | Less current portion of accrued warranty | | | (471 | ) | | | (731 | ) | Accrued warranty, less current portion | | $ | 275 | | | $ | 715 | |
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