Certain Balance Sheet Components

12 Months Ended

Dec. 31, 2020

Balance Sheet Related Disclosures [Abstract]

Certain Balance Sheet Components

A summary of accounts receivable from contracts with customers is as follows:

Accounts receivable, net
In thousands	December 31, 2020		December 31, 2019
Trade receivables (net of allowance of $1,312 and $3,064)	$	318,269	$	415,887
Unbilled receivables	51,559		57,038
Total accounts receivable, net	$	369,828	$	472,925

Allowance for credit losses account activity	Year Ended December 31,
In thousands	2020		2019		2018
Beginning balance	$	3,064	$	6,331	$	3,957
Provision for (release of) doubtful accounts, net	(299)		(1,511)		3,874
Accounts written-off	(1,463)		(1,749)		(1,281)
Effect of change in exchange rates	10		(7)		(219)
Ending balance	$	1,312	$	3,064	$	6,331

Inventories
In thousands	December 31, 2020		December 31, 2019
Raw materials	$	114,058	$	120,861
Work in process	8,094		11,105
Finished goods	60,225		95,930
Total inventories	$	182,377	$	227,896

Property, plant, and equipment, net
In thousands	December 31, 2020		December 31, 2019
Machinery and equipment	$	334,050	$	323,003
Computers and software	115,776		109,924
Buildings, furniture, and improvements	155,676		149,471
Land	14,303		14,988
Construction in progress, including purchased equipment	31,425		54,490
Total cost	651,230		651,876
Accumulated depreciation	(443,414)		(418,648)
Property, plant, and equipment, net	$	207,816	$	233,228

Depreciation expense	Year Ended December 31,
In thousands	2020		2019		2018
Depreciation expense	$	52,579	$	50,114	$	50,784