Property, Plant and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

11. Property, Plant and Equipment

The table below sets forth the reclassification and components of property, plant and equipment as of December 31, 2017 and 2016:

(in thousands)	2017		2016		Estimated useful life
Land and land improvements	$14,853		$13,339		25 years for improvements
Buildings	230,987		214,086		25 to 40 years
Building under capital lease	8,140		8,140		7 years
Machinery and equipment	950,519		842,921		5 to 15 years
Furniture and fixtures	8,861		7,632		5 years
Computer and other equipment	15,610		15,264		3 to 10 years
Software	57,847		54,212		5 to 8 years
Capital expenditures in progress	63,951		66,900
Property, plant and equipment, gross	1,350,768		1,222,494
Accumulated depreciation and amortization	(896,466	)	(799,930	)
Property, plant and equipment, net	$454,302		$422,564

Depreciation expense was $61.5 million in 2017, $58.1 million in 2016, and $53.0 million in 2015. Software amortization is recorded in Selling, general, and administrative expense and was $3.6 million in 2017, $4.0 million in 2016, and $6.5 million in 2015. We include amortization of the capital lease in depreciation expense. Accumulated amortization of the capital lease was $2.4 million and $0.9 million as of December 31, 2017 and 2016, respectively.

Capital expenditures, including purchased software, were $87.6 million in 2017, $73.5 million in 2016, and $50.6 million in 2015. Unamortized software cost was $7.6 million and $7.2 million as of December 31, 2017 and 2016, respectively. Expenditures for maintenance and repairs are charged to income as incurred and amounted to $19.1 million in 2017, $16.6 million in 2016, and $16.6 million in 2015.