Property, Plant and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Note 7. Property, Plant and Equipment

Property, plant and equipment are comprised of the following amounts:

	As of December 31,
	2017		2016
Land and buildings	$	54,833	$	51,992
Machinery and equipment		302,470		251,295
Construction in progress		14,346		10,786
		371,649		314,073
Less—accumulated depreciation		112,369		83,980
Property, plant and equipment, net	$	259,280	$	230,093

During the year ended December 31, 2017, we acquired $14.0 million in property, plant and equipment with the Vandalia acquisition. During the year ended December 31, 2015, we acquired $58.1 million in property, plant and equipment with the two acquisitions completed during 2015.

For the years ended December 31, 2017, 2016, and 2015, depreciation expense was $28.9 million, $24.7 million, and $20.1 million, respectively.