Certain Balance Sheet Components



Accounts receivable, net	September 30, 2013		December 31, 2012
	(in thousands)
Trade receivables (net of allowance of $8,227 and $7,372)	$	316,732	$	329,352
Unbilled receivables	32,560		45,974
Total accounts receivable, net	$	349,292	$	375,326

At September 30, 2013 and December 31, 2012, $3.4 million and $20.0 million, respectively, were recorded within trade receivables as billed but not yet paid by customers, in accordance with contract retainage provisions. At September 30, 2013 and December 31, 2012, contract retainage amounts that were unbilled and classified as unbilled receivables were $6.6 million and $11.1 million, respectively.

At September 30, 2013, long-term unbilled receivables totaled $2.4 million. These long-term unbilled receivables are classified within other long-term assets, as collection is not anticipated within the following 12 months. We had no long-term billed contract retainage receivables at September 30, 2013, as we expect to collect all contract retainage receivables within the following 12 months. We had no long-term unbilled receivables or long-term billed contract retainage receivables at December 31, 2012.



Allowance for doubtful account activity	Three Months Ended September 30,						Nine Months Ended September 30,
	2013			2012			2013			2012
	(in thousands)
Beginning balance	$	6,948		$	5,381		$	7,372		$	6,049
Provision (release) of doubtful accounts, net	1,290			(124		)	1,461			(414		)
Accounts written-off	(164		)	(53		)	(467		)	(314		)
Effect of change in exchange rates	153			151			(139		)	34
Ending balance	$	8,227		$	5,355		$	8,227		$	5,355



Inventories	September 30, 2013		December 31, 2012
	(in thousands)
Materials	$	112,148	$	92,038
Work in process	12,654		12,568
Finished goods	69,900		66,113
Total inventories	$	194,702	$	170,719

Our inventory levels may vary period to period as a result of our factory scheduling and the timing of contract fulfillments, which may include the buildup of materials in preparation for customer orders or finished goods for shipment.

Consigned inventory is held at third-party locations; however, we retain title to the inventory until purchased by the third-party. Consigned inventory, consisting of raw materials and finished goods, was $3.4 million and $5.0 million at September 30, 2013 and December 31, 2012, respectively.



Property, plant, and equipment, net	September 30, 2013			December 31, 2012
	(in thousands)
Machinery and equipment	$	302,216		$	287,791
Computers and software	102,496			84,980
Buildings, furniture, and improvements	146,704			146,191
Land	25,075			25,318
Construction in progress, including purchased equipment	17,970			26,097
Total cost	594,461			570,377
Accumulated depreciation	(345,389		)	(315,165		)
Property, plant, and equipment, net	$	249,072		$	255,212



Depreciation expense and capitalized interest	Three Months Ended September 30,				Nine Months Ended September 30,
	2013		2012		2013		2012
	(in thousands)
Depreciation expense	$	14,330	$	15,656	$	42,370	$	45,989
Capitalized interest	—		—		64		—

In conjunction with the upgrade of our global enterprise resource planning (ERP) software systems, we capitalized $64,000 of interest for the nine months ended September 30, 2013. In the third quarter of 2013, we reclassified our ERP software from Construction in progress to Computers and software.