PROPERTY, PLANT AND EQUIPMENT

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT

A summary of property, plant and equipment as of December 31, 2017 and 2016 is as follows (in thousands):

	December 31,
	2017			2016
Land	$	6,698		$	7,429
Buildings and leasehold improvements	47,924			42,257
Machinery and equipment	261,343			233,063
Furniture and fixtures	9,405			8,431
Capitalized ERP system development costs	46,637			44,876
Computers and computer software	13,052			11,775
Automobiles	5,070			5,370
Construction in progress	12,613			12,997
Total	402,742			366,198
Accumulated depreciation and amortization	(199,523		)	(163,068		)
Property, plant, and equipment, net	$	203,219		$	203,130

Depreciation expense for the years ended December 31, 2017 and 2016, the seven months ended December 31, 2015 and the year ended May 31, 2015 was $35.7 million, $33.5 million, $13.9 million and $19.0 million, respectively.

At the end of 2013, we initiated the design and implementation of a new ERP system, which was substantially installed by the end of 2017. Amortization of the ERP system development costs began in March 2017 and is computed by the straight-line method. Through December 31, 2017, we have capitalized $46.6 million associated with the project that includes $1.6 million of capitalized interest, and we have recognized $2.6 million of amortization expense.