Property, Plant and Equipment

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

14. Property, Plant and Equipment

The table below sets forth the components of property, plant and equipment as of December 31, 2020 and 2019:

(in thousands)	2020		2019		Estimated useful life
Land and land improvements	$	15,611	$	14,168	25 years for improvements
Buildings	246,137		227,875		15 to 40 years
Right of use assets	10,971		16,686		10 to 15 years
Machinery and equipment	1,076,092		1,020,348		5 to 15 years
Furniture and fixtures	8,638		8,126		5 years
Computer and other equipment	19,294		18,808		3 to 10 years
Software	62,400		60,995		5 to 8 years
Capital expenditures in progress	46,228		45,588
Property, plant and equipment, gross	1,485,371		1,412,594
Accumulated depreciation and amortization	(1,036,817)		(946,132)
Property, plant and equipment, net	$	448,554	$	466,462

Depreciation expense was $63.3 million in 2020, $62.1 million in 2019, and $68.8 million in 2018. Software amortization is recorded in Selling, general, and administrative expense and was $2.1 million in 2020, $2.4 million in 2019, and $3.2 million in 2018.

Capital expenditures, including purchased software, were $42.4 million in 2020, $68.0 million in 2019, and $82.9 million in 2018. Unamortized software cost was $4.8 million in 2020, $5.3 million and $6.9 million as of December 31, 2019 and 2018, respectively. Expenditures for maintenance and repairs are charged to income as incurred and amounted to $17.7 million in 2020, $19.8 million in 2019, and $19.4 million in 2018.