Property, Plant and Equipment, net

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, plant and equipment consisted of the following:



	December 31,
(in thousands)	2017			2016
Land	$	33,087		$	32,127
Buildings and site improvements	212,817			183,882
Leasehold improvements	4,684			5,550
Machinery and equipment	300,334			248,861
	550,922			470,420
Less accumulated depreciation and amortization	(299,907		)	(273,302		)
	251,015			197,118
Capital projects in progress	22,005			35,692
	$	273,020		$	232,810

Included in property, plant and equipment at December 31, 2017 and 2016, are fully depreciated assets with an original cost of $189.9 million and $166.7 million, respectively. These fully depreciated assets are still in use in the Company’s operations.

The Company capitalizes certain development costs associated with internal use software, including external direct costs of materials and services and payroll costs for employees devoting time to a software project. As of December 31, 2017 and 2016, depreciable capitalized software development costs were $20.5 million and $4.6 million, respectively, and included in capital projects in progress at December 31, 2017 and 2016, were software in development costs of $12.2 million and $13.5 million, respectively. The approximate $29.0 million increase in buildings and site improvements was primarily related to $21.2 million improvement costs associated with the manufacturing facility in West Chicago and the expansion of the McKinney facility.

Depreciation expense, including depreciation of equipment and software acquired through capital lease arrangements, was $27.3 million, $21.6 million and $20.4 million for the years ended December 31, 2017, 2016 and 2015, respectively.