| Property, Plant and Equipment, Net |
| | | 7. | Property, Plant and Equipment, Net |
| | | | | | | | | | As of December 31, | | 2016 | | 2015 | Plant, machinery, furniture and fixtures | $ | 314,880 |
| | $ | 305,763 |
| Building and leasehold improvements | 14,420 |
| | 14,698 |
| Land and land improvements | 60,863 |
| | 60,687 |
| Construction in progress | 8,451 |
| | 6,660 |
| Property, plant and equipment, gross | 398,614 |
| | 387,808 |
| Less: accumulated depreciation | (147,513 | ) | | (136,899 | ) | Property, plant and equipment, net | $ | 251,101 |
| | $ | 250,909 |
|
Depreciation expense for the years ended December 31, 2016, 2015 and 2014 was $16.0 million, $15.9 million and $14.5 million, respectively. Property, plant and equipment include the following amounts under capital leases: | | | | | | | | | | As of December 31, | | 2016 | | 2015 | Plant, machinery, furniture and fixtures | $ | 16,664 |
| | $ | 16,457 |
| Building and leasehold improvements | 4,719 |
| | 4,719 |
| Land and land improvements | 251 |
| | 251 |
| Property, plant and equipment, gross | 21,634 |
| | 21,427 |
| Less: accumulated amortization | (10,186 | ) | | (9,572 | ) | Property, plant and equipment, net | $ | 11,448 |
| | $ | 11,855 |
|
Amortization expense on capital leased assets is included in depreciation expense and for the years ended December 31, 2016, 2015 and 2014 was $1.5 million, $1.4 million and $1.3 million, respectively. |