| Revenue |
Revenue The Company differentiates revenue and cost of revenue based on whether the source of revenue is attributable to products, rentals or services. Revenue and cost of revenue by source are as follows (in thousands): | | | | | | | | | | | | | | | | | | Three months ended September 30, | | Nine months ended September 30, | | 2015 | | 2014 | | 2015 | | 2014 | Revenue: | | | | | | | | Products | $ | 76,555 |
| | $ | 92,708 |
| | $ | 217,237 |
| | $ | 257,415 |
| Rentals | 7,574 |
| | 16,966 |
| | 28,146 |
| | 45,954 |
| Services | 3,813 |
| | 7,087 |
| | 11,963 |
| | 21,284 |
| | $ | 87,942 |
| | $ | 116,761 |
| | $ | 257,346 |
| | $ | 324,653 |
| Cost of revenue: | | | | | | | | Products | $ | 49,520 |
| | $ | 57,315 |
| | $ | 145,387 |
| | $ | 155,048 |
| Rentals | 3,387 |
| | 8,272 |
| | 13,315 |
| | 22,444 |
| Services | 2,160 |
| | 3,074 |
| | 6,283 |
| | 9,042 |
| Depreciation | 1,648 |
| | 2,022 |
| | 5,355 |
| | 6,051 |
| | $ | 56,715 |
| | $ | 70,683 |
| | $ | 170,340 |
| | $ | 192,585 |
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