Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property and equipment

Property and equipment are summarized as follows (in thousands):

	Estimated Useful Life	December 31,
		2017			2016
Land	—	$	22,765		$	22,326
Buildings	30 years	167,645			162,701
Machinery and equipment	3 to 7 years	275,688			258,023
Office equipment and other	3 to 10 years	104,064			103,798
		570,162			546,848
Less accumulated depreciation		(306,166		)	(275,063		)
		$	263,996		$	271,785

Depreciation expense for the years ended December 31, 2017, 2016 and 2015 was $42.3 million, $37.8 million and $32.5 million, respectively.