Certain Balance Sheet Components



Accounts receivable, net	September 30, 2016		December 31, 2015
	(in thousands)
Trade receivables (net of allowance of $4,254 and $5,949)	$	319,929	$	298,550
Unbilled receivables	48,781		32,345
Total accounts receivable, net	$	368,710	$	330,895

At September 30, 2016 and December 31, 2015, $4.6 million and $0.7 million, respectively, were recorded as contract retainage receivables within trade receivables, in accordance with contract retainage provisions. At September 30, 2016 and December 31, 2015, contract retainage receivables that were unbilled and classified as unbilled receivables were $5.4 million and $3.5 million, respectively. These contract retainage receivables within trade receivables and unbilled receivables are expected to be collected within the following 12 months.

At September 30, 2016 and December 31, 2015, long-term billed contract retainage receivables were $0.4 million. At September 30, 2016 and December 31, 2015, long-term unbilled contract retainage receivables were $3.8 million and $3.6 million, respectively. These long-term billed and unbilled contract retainage receivables are classified within other long-term assets, as collection is not anticipated within the following 12 months. We consider whether collectability of such retainage is reasonably assured in connection with our overall assessment of the collectability of amounts due or that will become due under our contracts.



Allowance for doubtful accounts activity	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
	(in thousands)
Beginning balance	$	3,939		$	5,422		$	5,949		$	6,195
Provision (release) for doubtful accounts, net	353			(141		)	265			(111		)
Accounts written-off	(77		)	(162		)	(1,919		)	(503		)
Effect of change in exchange rates	39			(160		)	(41		)	(622		)
Ending balance	$	4,254		$	4,959		$	4,254		$	4,959



Inventories	September 30, 2016		December 31, 2015
	(in thousands)
Materials	$	112,507	$	111,191
Work in process	9,919		9,400
Finished goods	67,127		69,874
Total inventories	$	189,553	$	190,465

Consigned inventory is held at third party locations; however, we retain title to the inventory until it is purchased by the third party. Consigned inventory, consisting of raw materials and finished goods, was $2.1 million and $2.6 million at September 30, 2016 and December 31, 2015, respectively.



Property, plant, and equipment, net	September 30, 2016			December 31, 2015
	(in thousands)
Machinery and equipment	$	290,395		$	289,015
Computers and software	105,791			104,310
Buildings, furniture, and improvements	127,297			127,531
Land	18,069			19,882
Construction in progress, including purchased equipment	26,956			32,639
Total cost	568,508			573,377
Accumulated depreciation	(387,641		)	(383,121		)
Property, plant, and equipment, net	$	180,867		$	190,256



Depreciation expense	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
	(in thousands)
Depreciation expense	$	11,086	$	11,129	$	32,561	$	34,060