Property, Plant and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

Property, plant and equipment consist of the following at December 31:

	2017			2016
Land	$	4,027		$	4,027
Building and improvements	91,766			90,780
Machinery and equipment	219,675			205,674
Construction in progress	7,837			7,229
	323,305			307,710
Less:  Accumulated depreciation	(207,076		)	(185,681		)
	$	116,229		$	122,029

We lease various manufacturing facilities, office facilities and equipment under operating and capital leases.  Leasehold improvements related to these facilities are included in building and improvements above. Rental expense on operating leases was approximately $6,507, $6,043 and $5,464 for the years ended December 31, 2017, 2016 and 2015, respectively. During 2017, we entered into capital lease obligations of $762 in connection with the purchase of computer equipment. The aggregate future minimum lease commitments for leases at December 31, 2017 are as follows:

	Operating Leases		Capital Leases
2018	$	6,832	$	246
2019	6,117		246
2020	3,448		116
2021	2,239		—
2022	2,099		—
Thereafter	3,613		—